Customer Relationship Management (CRM) systems help organizations manage leads and existing customers in the most efficient way possible to deliver a better customer experience and streamline their sales operations. CRM vendors help analyze customer interactions and keep track of data throughout the interaction lifecycle. Programmatic access to this data is becoming key since CRM users expect integrated solutions. CRMs APIs like Salesforce, Microsoft Dynamics, Pipedrive, and many more open up this data programmatically towards developers, unlocking unlimited possibilities.

In 2025, the CRM API landscape has split between established leaders pushing AI enhancements and emerging platforms built API-first from the ground up. AI integration is now table stakes. Therefore, expect endpoints for predictive lead scoring, automated task generation, and conversational intelligence across all major platforms.

CRMs often provide many integrations, helping users define workflows to orchestrate actions across different tools. However, sometimes existing integrations don’t fit the use case you as a user have in mind. A CRM API can provide deeper extensibility, enabling you to leverage the full system of record for customer data. This could make integrating with a CRM API the best option to create new workflows.

What's New in CRM APIs (2025)

Real-time beats polling. Webhook-first architectures and streaming APIs are replacing traditional polling mechanisms. If you're still polling every 5 minutes, you're already behind. Security requirements have escalated. End-to-end encryption, granular audit logs, and compliance tooling are standard. OAuth 2.1 adoption is accelerating, with many providers deprecating older authentication methods by Q3 2025.

GraphQL adoption varies wildly. While monday.com and newer platforms embrace it fully, legacy systems maintain REST-only approaches. Plan for hybrid architectures.

Benefits of Using a CRM API

There are many reasons why a developer may want to integrate with a CRM API, as opposed to utilizing a UI or an existing integration. Developers with API access could integrate the CRM with other platforms, export valuable data for sales teams, or build new event-driven workflows. Here are some benefits:

• Save time on repetitive tasks: For one, calling a CRM API could be a huge time-saver — CRM APIs open a programmatic doorway to help automate many manual tasks, like finding customer data, or generating reports.
• Leverage customer data: Developers with API access could export valuable CRM data, such as customer email information, to plug into an event-driven flow to notify end customers. This could increase customer satisfaction and product stickiness.
• Inform sales department: Developers can utilize CRM APIs to export valuable sales data, helping product managers visualize important metrics to gauge success. With an event-driven workflow, such a process could be automatically initiated.
• Bridge missing integrations: CRMs connect with various moving components; therefore, APIs are often essential in partner integration. If your CRM provider does not provide a pre-existing integration, utilizing the API may be the only way to integrate your CRM with other platforms.
• Extend to other environments: APIs are client-agnostic. Thus, by using a RESTful API, an organization could bring CRM data into any custom environment. This could include local platforms, company-wide intranets, or other interfaces.
• Aggregation: If you're building a SaaS product yourself, you will want to integrate many CRM APIs depending on the CRMs used by your customers. Aggregating specific domains, like [CRM Data] (https://www.apideck.com/crm-api), is something that Unified APIs do well, too. This removes the need to integrate with multiple CRM APIs, and you still benefit by being natively integrated and be present in CRM partners' marketplaces to promote your integration.

25 CRM APIs

Today, there are a multitude of CRMs on the market — 500+ CRMs APIs. Some of them are vertical specific. Therefore, there are many CRM APIs available! Depending on your customer base, most of these CRMs will be requested daily if you don’t already integrate with them. Most CRMs provide APIs in different API styles like REST, SOAP, GraphQL, or OData.

Whether you are searching for an extensible CRM, or you are merely curious about what sort of connections yours offers, we've got you covered. Here are 25+ CRM APIs available right now:

Salesforce CRM API

Salesforce is arguably the world's #1 CRM software in terms of adoption. It provides a comprehensive business ecosystem with all business products which can be seamlessly integrated. It comes with a mobile application and lets you manage leads, customer engagement, workflow rules, automation, and many other functionalities.

New in 2025: Salesforce's Agentforce framework provides AI agent endpoints for autonomous workflow deployment. Enhanced Einstein API offers contextual recommendations. Mandatory encryption for API responses by July 2025. GraphQL API now in beta alongside REST/SOAP.

The API is very flexible in this case and provides a massive list of actions. It is available in REST and SOAP. The SOAP API is restricted to search only, while the REST API can be used to do almost anything. Salesforce lists ten integrations with services such as Gmail, MailChimp, and Dropbox, but many other extensions are available through the Salesforce AppExchange.

Github Stars: 2k Number of Integrations: Thousands on AppExchange marketplace

Features:

• An omnichannel platform to grow your client base
• Social media integrations
• Agentforce endpoints: /services/data/v62.0/agent/
• Rate limits: 100,000 daily API calls (Enterprise)

Zoho CRM API

Zoho CRM is a robust CRM software that handles many business needs. This CRM comes with a REST API that can be integrated with any third-party software. Being one of the major CRM players, the API offers a lot like organization management, role management, user management, records, and other features.

New in 2025: Zoho's Zia AI platform now offers Vision API for document processing, contextual task generation endpoints, and advanced lead scoring with explanations. Blueprint API v3 enables complex workflow automation.

One of the best parts of Zoho is that it provides a free developer account you can use for testing purposes and explore Zoho features, create your applications and learn how to integrate the Zoho API. This CRM API also offers an SDK for languages like PHP, NodeJS, Python, and others.

The CRM comes with many integrations such as GSuite, Slack, Office365, WhatsApp, and Zoom. You can check out the complete list of integrations here. You can also check out their Git repository here.

Number of integrations: 95 Rate limits: 50,000 credits/day (varies by plan)

Features:

• The API provides a lot of customizations.
• Comes with many integrations.
• The documentation is straightforward and easy to use.
• Comes with SDKs too.
• New Zia endpoints: /zia/v2/predictions/

HubSpot CRM API

HubSpot CRM is a fine solution for your business needs. The CRM has got a decent UI and can be easily integrated with other HubSpot products. The CRM uses a freemium approach, which means it's free to use software but with the paid add-on to extend the functionalities.

New in 2025: HubSpot's Breeze Copilot integration provides conversational interfaces through dedicated API endpoints. New account activity timeline endpoints and validation APIs for data quality checks. Enhanced webhook reliability with 99.95% SLA.

The HubSpot CRM API comes with many functionalities like contact management, company management, lead management, tickets, product, and the ability to create custom objects. There's also a JS SDK available to make calls.

Github Stars: 38931 Number of Integrations: 69 Rate limits: 500 requests/10 seconds (Professional)

Features:

• Free to use with basic functionalities
• Comes with a variety of integrations
• Breeze Copilot APIs: /automation/v4/breeze/
• CRM v4 endpoints: /crm/v4/objects/

Copper CRM API

Copper CRM (formerly ProsperWorks CRM) is closely related to the G Suite environment. The CRM is best suited for small to mid-sized businesses. It comes with a 14 days free trial and does not require you to use your credit for sign up. It is also known as Google's recommended CRM as it seamlessly integrates with the G Suite and its apps.

This CRM's API is also straightforward to use, especially since a Postman collection is available to test it out easily. It allows you to manage leads, companies, tasks, activities, etc. There are SDKs available for different languages — you can check them out here. Copper CRM supports the integration of some popular software, like Slack, Hubspot, MailChimp, etc. You can check out the list of integrations here.

Github Stars: 754 Number of Integrations: 80 Enhanced Google Workspace integration in 2025

Features:

• Best suited for G Suite
• Easy to use API
• Improved custom object support

Close.io API

Close is another fine CRM, specifically for startups. Founded in 2013, Close CRM provides functionalities like calendar reminder, email marketing, marketing automation, segmentation, and more. The UI of this CRM is very similar to AdminLTE but with added features.

New in 2025: Improved calling APIs with predictive dialer support. SMS automation endpoints. Enhanced reporting APIs.

The API of this CRM includes all the functionalities that a basic CRM has. It also supports bulk emails, reporting, managing memberships, etc. Close CRM also has an official Python client you can use to consume the API. On the same Git page, you can find some unofficial clients as well. The CRM can be integrated with 80+ services like Zoom, Slack, Gmail, Zapier, etc. You can check out the list of integrations here.

Github Stars: 51 Number of Integrations: 86

Features:

• It lets you make calls, emails, SMS from a single UI
• Supports automation like marketing, email, etc
• Sales forecasting
• Predictive dialer API support

Salesflare API

Salesflare is a simple CMS with a very intelligent email outreach application being used by thousands of small and mid-sized businesses. It lets you automate your customers’ data entry process like social profiles, contact numbers, profile data, company databases, etc.

New in 2025: Email intelligence improvements and social enrichment APIs for better contact data.

The Salesflare API is based on OpenSpec API and includes a good list of features like task management, account management, contact management, meetings management, etc. The authentication is based on the API key like other CMS. Salesflare comes with 182 integrations and custom apps as well. You can check out the list of integrations here.

Number of Integrations: 184 Github Stars: 307

Features:

• Forecasting
• Custom Reporting
• Social network integrations
• Enhanced data enrichment endpoints

Microsoft Dynamics API

As the name suggests, Microsoft Dynamics is developed by Microsoft. It focuses on sales, marketing, and help-desk services. The open-source CRM is based on the .NET framework and is available in multiple languages. It also provides apps for iOS, Android, as well as Windows phones.

New in 2025: Microsoft's Copilot integration provides unified customer profile API across all channels. New Teams integration APIs for collaborative selling. Enhanced OData v4 support with better filtering.

Microsoft Dynamics comes with a big set of REST API endpoints, which give you access to services like customer service, store, eCommerce management, field services, human resources, marketing, and other areas.

Number of Integrations: 59 Github Stars: N/A Rate limits: 60,000 requests per user/5 minutes

Features:

• It comes with online as well as offline capability.
• It can be integrated with almost all of the Microsoft products.
• Copilot action endpoints: /api/copilot/v1/
• Unified customer insights: /api/insights/v2/

Pipedrive API

Pipedrive offers a CRM tool for small-sized companies. The Pipedrive UI visualizes customer data to help businesses make informed decisions. The UI is minimalistic and mostly focuses on visual pipelines for deals.

New in 2025: Pipeline velocity calculation endpoints for better sales analytics. Automated deal routing APIs. Enhanced custom field support (100+ fields). New marketplace app APIs for third-party developers.

The API of this CRM uses an API key for the authentication and provides many functionalities like call log management, currency conversion, deals management, file management, etc. It comes with 251 integrations, like Zapier, Zoom, and Slack. You can check out the full list of integrations here. They also have client libraries for NodeJS, PHP, Python, .NET, Ruby, JavaScript, and Laravel.

Number of Integrations: 251 Github Stars: 135 Rate limits: 1000 requests/2 seconds (OAuth apps)

Features:

• Email tracking
• Marketing automation
• Custom reporting
• Pipeline analytics: /v2/pipelines/analytics/
• Automation endpoints: /v2/automations/

Insightly API

Insightly is a visually attractive and intuitive CRM with a wide range of functionalities and a large number of integrations. The unique feature of this CRM is that it assigns a customer support manager to new customers to get them up and running.

New in 2025: Project management convergence with enhanced marketing automation APIs.

Insightly CRM uses a set of REST APIs, including functionalities like custom reporting, data sync, workflow automation, etc. It comes with 77 integrations such as Gmail, Google Apps, and MailChimp. You can check out the complete list of integrations here.

Number of Integrations: 77 Github Stars: 22

Features:

• Amazing UI
• Custom data capture
• Free smartphone app
• Improved project-CRM integration

SugarCRM API

SugarCRM is another one of the most popular CRMs available in the market with more than 2 million users. It comes with an industry-leading customer experience and a simple UI. The plan starts at $40 per month and is available on all platforms.

New in 2025: Better REST performance with optimized endpoints. Enhanced mobile APIs. Sugar Market integration for unified marketing and sales.

SugarCRM comes with a good set of REST API endpoints, which support email management, user management, task management, etc. The authentication is based on Basic Auth and exchanges tokens for the proceeding requests. It can be integrated with more than 72 services, like MailChimp, Zapier, Gmail, etc. You can check out the list of all the integrations here. SugarCRM also offers a PHP client to connect with the API.

Number of Integrations: 72+ Github Stars: 28

Features:

• Easily automate your marketing process
• Custom reporting
• Improved API response times

AgileCRM API

AgileCRM is an all-in-one solution designed specifically for small-sized businesses to help them in marketing, sales, and customer relationships. It is available on web, android, and iOS platforms. AgileCRM comes with REST API along with clients for languages like PHP, Java, JavaScript, C#, Ruby, NodeJS, iOS, and Python. The API uses an API key for authentication, and the documentation is also very well written. It comes with 90 integrations like Gmail, Facebook, Twitter, etc. You can check out the list of all integrations here.

Number of Integrations: 90 Github Stars: 68

Features:

• Auto-sync
• Marketing automation

Freshworks CRM API (previously Freshsales.io)

Launched in 2011, Freshworks is another popular player in the CRM market. Many big companies like Dyson, Asus, and FabHotels use this CRM. It delivers a great experience across marketing and sales fields, including functionalities like marketing automation, salesforce automation, live chat, and calling.

New in 2025: Enhanced omnichannel APIs for unified customer engagement. AI-powered lead scoring. Improved marketplace with 50+ new integrations.

The CRM also allows you to create a free account so that you can play around with some features. The Freshworks API is very extensive and lets you raise tickets, track conversations, manage skills, agents, roles, organizations, create mailboxes, send bulk emails, and more. This CRM doesn't support much integration as it already has a lot of features inbuilt. You can check out the list of integrations here. You can download many packages like freshchat-android, which you can use in your Android app. You can check out others at the Git repo here.

Github Stars: 23 Number of Integrations: 74+ with enhanced marketplace

Features:

• It supports AB testing
• Comes with a heatmap that you can use to check the hot products
• Live chat
• AI-powered scoring endpoints

Act! API

Act! is a CRM software used to manage clients and prospect details in a single place, and can be accessed by multiple users. It is one of the oldest CRMs available in the market right now. It has three editions: Act Pro, Act Premium, and Act 365, which is a hosted version of Act.

The API of this CRM can be used to manage stocks, add/edit contacts, manage calendar, import analytics data, manage contacts, and others. The act comes with integrations such as Slack, Facebook, Twitter, Shopify, etc. You can check out the list of integrations here.

Github Stars: N/A Number of Integrations: 20

Features:

• One of the most affordable CRM in the market.
• Available as a web app, SAAS, and independent Windows software.

Zendesk Sell API

Zendesk Sell is a CRM software that comes with features like calling, messaging, email, etc. This CRM is used by a lot of major companies as well.

New in 2025: Unified customer view across Sell and Support platforms. Improved search APIs with better filtering and performance.

The Zendesk Sell API is divided into four parts: Core API, Sync API, Firehose API, and Search API. The Core API includes all the core functionalities that a CRM must have, like customer management, user management, tags management, analytics, etc. The Sync API lets you sync all the data with the cloud server. The Firehose API retrieves real-time user data. While the Search API is for query purposes.

The Zendesk Sell comes with 18 integrations like Shopify, TimeShift, etc. You can check out the list of integrations here. They also have a Github repository for their project where you can find integration packages for Zapier as well.

Number of Integrations: 18 Github Stars: 32

Features:

• Offers a very organized UI.
• The API provides almost all the functionalities which the UI provides.
• Automatically syncs the data with the server.
• Cross-platform customer data access

Teamleader API

Teamleader is a cloud-based CRM software mostly used by mid-sized to large-sized companies. It is a stand-alone CRM solution that can help businesses with sales automation, customer service, support, invoicing, etc. It allows the customers to set the appointment. It is equipped with features like ticketing, project management, and employee management as well.

The Teamleader API supports OAuth 2.0 for authentication and lets you manage contacts, calendar, invoicing, project, tracking, etc. The documentation is very well-written, with responses for each request in JSON. This CRM comes with 190 integrations such as Gmail, Office365, MailChimp, etc. You can check out the full list of integrations here.

Number of Integrations: 190 Github Stars: NA

Features:

• Supports a lot of integrations.
• Very simple UI with a lot of customizations.

Airtable API

While Airtable is not a pure CRM, it can be used as one. With Airtable, you can organize anything like projects, ideas, customers, or even your team. It provides a spreadsheet-like UI that is very easy to use. Airtable lets you use different widgets and match them with different functionalities. It also comes with ready-to-use templates for different team sizes. Airtable provides a kanban-like overview of all task statuses.

Airtable allows you to create small custom applications that can meet the needs of your team. The CRM comes with a REST API, which is pretty easy to use and has accompanying YouTube tutorials.

Airtable also comes with a NodeJS package to access all the data, leads, inventory, and todos you use in your web application. You can check out the GitHub repository for more information. Unfortunately, it doesn't come with a free developer account.

GitHub Stars: 1.2k Number of integrations: 60 (You can check out all the integrations here).

Features:

• It lets you create custom applications.
• The API can be used to manage almost every functionality.
• YouTube tutorials are there to help you with the API integration.

New & Emerging CRMs

ServiceNow CRM

ServiceNow, traditionally known for IT service management, has expanded into full CRM capabilities targeting enterprises that want unified sales and service operations. The platform leverages their existing workflow engine to create sophisticated customer journeys that span across departments, breaking down silos between sales, service, and operations teams.

Their AI Control Tower acts as a centralized intelligence hub, analyzing patterns across all customer touchpoints to predict outcomes and recommend next best actions. The API-first design means every feature available in the UI can be programmed, making it ideal for enterprises with complex integration requirements.

Features:

• AI Control Tower for predictive analytics
• Unified sales/service workflows
• Agent-driven automation APIs
• Real-time streaming for all data changes

Key endpoints: /api/now/crm/v1/, /api/now/ai/control/, /api/now/workflows/

Rate limits: Enterprise-negotiable, typically 100+ requests/second

Clarify

Clarify represents a new generation of CRM built with AI as the foundation, not an add-on. Unlike traditional CRMs that bolt on AI features, Clarify processes every piece of customer data through machine learning models to surface insights automatically. This means developers don't need separate API calls for intelligence since it's embedded in every response.

The platform excels at understanding customer intent and predicting behavior without manual rule creation. Their natural language query support allows developers to request data using plain English instead of complex query parameters, significantly reducing integration complexity for teams without deep CRM expertise.

Features:

• Predictive segmentation APIs
• Personalized engagement endpoints
• Automated data enrichment
• Natural language query support

Key endpoints: /v1/segments/predict/, /v1/engage/personalize/, /v1/insights/

Rate limits: 10,000 requests/hour

monday.com CRM

monday.com evolved from project management into CRM by recognizing that customer relationships are essentially projects with longer timelines. Their Work OS approach means CRM data lives alongside project tasks, making it perfect for agencies and service businesses where client work and relationships intertwine.

The GraphQL-first API design provides exceptional flexibility and developers can query exactly the data they need without over-fetching. Their board-based structure might feel unconventional for CRM veterans, but it enables visual pipeline management that non-technical teams actually adopt.

Features:

• GraphQL-first API design
• Custom workflow automation
• Board-based data structures
• Real-time collaboration webhooks

GraphQL queries for boards, items, updates

Rate limits: Complexity-based (10,000 points/minute)

DevRev

DevRev challenges traditional CRM architecture by converging customer, product, and support data into a unified model. Built by former Nutanix executives, it treats customer relationships as inseparable from product usage and support interactions. A support ticket isn't separate from a sales opportunity; they're different views of the same customer object.

The platform's API-first philosophy means the UI literally uses the same APIs available to developers, ensuring complete feature parity. Their automatic API versioning eliminates breaking changes where old endpoints continue working while new features appear in versioned namespaces, solving a major pain point in CRM integrations.

Features:

• Converged data model (customers = users = tickets)
• Built-in RevOps analytics
• API-first architecture
• Automatic API versioning

Key endpoints: /v1/rev-objects/, /v1/analytics/cohorts/, /v1/automations/

Rate limits: 100 requests/second

Attio API

Attio represents the next generation of CRM with a spreadsheet-like flexibility that appeals to technical teams who've outgrown Notion databases but aren't ready for Salesforce complexity. Launched in 2019 and achieving rapid adoption, it offers the customizability of Airtable with the power of a proper CRM, allowing teams to model their exact business workflows without compromising on features.

The platform's AI-native approach means every interaction gets enriched automatically, from LinkedIn profiles to company data, while maintaining sub-50ms query performance across millions of records. Their REST API follows modern conventions with TypeScript SDK support, and uniquely, they offer an embeddable React framework for building custom applications directly within the CRM interface.

Features:

• Custom objects and attributes without code
• Real-time data enrichment (ARR, funding rounds, contact details)
• AI-powered relationship intelligence and summaries
• Embeddable TypeScript React apps within CRM
• Chrome extension for LinkedIn contact capture

Key endpoints: /v2/objects/, /v2/records/, /v2/lists/, /v2/webhooks/

Rate limits: Varies by plan, typically generous for API-first usage

Authentication: OAuth 2.0 or access tokens with granular scopes

Appian CRM

Appian approaches CRM as a subset of broader business process automation. Their low-code platform allows organizations to build custom CRM functionality that integrates deeply with existing enterprise systems without traditional development cycles. This makes it ideal for heavily regulated industries with unique compliance requirements.

The platform's process mining capabilities analyze how customer interactions actually flow through the organization, then optimize those paths automatically. RPA integration means repetitive tasks across legacy systems can be automated without API access, which is critical for enterprises with decades of technical debt.

Features:

• Process mining API integration
• Low-code automation endpoints
• Embedded RPA capabilities
• Enterprise governance controls

Key endpoints: /suite/api/v1/processes/, /suite/api/v1/records/

SuperOffice

SuperOffice targets European businesses with GDPR compliance built into the architecture, not bolted on. Based in Norway, they understand European data sovereignty requirements and offer on-premise deployment options that many US-based CRMs can't match. Every API endpoint includes privacy controls by default.

Their deep Microsoft integration goes beyond surface-level connectivity. Outlook becomes a full CRM client, and Exchange calendar integration handles complex meeting scheduling scenarios. This native Microsoft approach appeals to enterprises already invested in the Microsoft ecosystem but wanting alternatives to Dynamics.

Features:

• GDPR compliance in every endpoint
• Deep Outlook/Exchange integration
• Multi-language support (20+ languages)
• On-premise deployment options

4Degrees API

4Degrees built their CRM specifically for relationship-driven businesses like investment banking, consulting, and commercial real estate. The platform automatically builds relationship graphs from email and calendar data, scoring relationship strength based on interaction frequency, recency, and depth.

Their API exposes sophisticated relationship intelligence that traditional CRMs miss. Developers can query not just who knows whom, but how well they know them and through which connections. This network effect data proves invaluable for firms where warm introductions drive deals.

Features:

• Automated relationship strength scoring
• Email/calendar mining APIs
• Deal flow analytics
• Network effect calculations

Deepser

Deepser bridges the gap between IT service management and traditional CRM, perfect for MSPs and technical service providers who need both capabilities. The platform treats support tickets and sales opportunities as related entities, tracking the full customer lifecycle from initial problem to upsell opportunity.

Their API unifies ITSM and CRM operations, allowing developers to create workflows that span both domains. Asset tracking integration means you can tie customer relationships to specific hardware or software deployments, which is critical for technology service providers managing complex client environments.

Features:

• Unified ticketing and sales APIs
• SLA management endpoints
• Asset tracking integration
• Multi-channel support integration

ClickUp CRM API

ClickUp expanded from project management into CRM by recognizing that many businesses manage clients and projects in tandem. Their approach allows teams to track deals alongside deliverables, making it ideal for agencies and professional services firms where winning the deal is just the beginning.

The API treats CRM objects as specialized task types, enabling sophisticated automation between sales and delivery. Custom field relationships allow modeling complex business logic without code, while maintaining the flexibility that made ClickUp popular for project management.

Features:

• Unified tasks and deals
• Custom field relationships
• Time tracking integration
• Document collaboration APIs

Aircall API

Aircall flips the traditional CRM model by making communication the core, not contacts. Built for call centers and sales teams that live on the phone, every feature revolves around conversation intelligence. The CRM functionality wraps around call data rather than treating calls as an afterthought.

Their API provides real-time call events and transcription, enabling developers to build sophisticated conversation analytics. Integration with traditional CRMs is seamless, but Aircall's strength lies in voice-first workflows that other CRMs struggle to support natively.

Features:

• Call recording/transcription APIs
• Real-time call events
• Conversation intelligence endpoints
• Omnichannel analytics

Excel and Google Sheets 😬

A common fact is that many businesses may not even be adopting a CRM platform. Many companies simply use an Excel or Google spreadsheet to track their leads and customer journeys. This isn't that scalable for a large enterprise. However, spreadsheets are relatively easy to integrate with third-party providers.

Through the Excel API (one of Microsoft Graph's many API), developers can programmatically access data within spreadsheets and perform calculations. Calling upon customer data stored in Excel sheets could be very useful for populating reports or generating dashboards.

Github Stars: N/A Number of Integrations: ∞

1CRM API

1CRM is a cloud-based CRM solution that offers functionalities like sales management, customer service, and business operations. It combines a traditional CRM with an order management system to track the orders, generate invoices, and send quotes.

This CRM offers both a REST API as well as client libraries. The documentation is well-written, and the API supports Basic authentication. The API only supports CRUD functionalities for the records, unlike other APIs that support more functionalities.

You can get the PHP as well as Go client from their Git repository, which you can use to perform CRUD operations. 1CRM supports 16 integrations like Microsoft Teams, Zoom, PayPal, Zapier, WordPress, etc. You can check out the full list of integrations here.

Github Stars: 4 Number of Integrations: 16

Features:

• Provides extensive customization features.
• Changelog is available as a standard feature.
• Automatic reminders are available to all user accounts.

Sellsy API

Sellsy is not only a CRM but also lets you manage your eCommerce website, manage stocks, purchases, etc. It includes features like sales tracking, lead generation, invoicing, customer management, 365 views of customers, POS, etc.

The API of this CRM is very comprehensive. All the endpoints are provided with a sample JSON response to make the API easier to understand. Sellsy supports 81 integrations, for example, Gmail, Ringover, Xeno, etc. You can check out the full list of integrations here. They also have a PHP client which you can use to integrate it into your application.

Number of Integrations: 81 Github Stars: 12

Features:

• It allows you to create quotes
• Automated task distribution
• Comes with a document builder

Lawmatics API

Lawmatics is an excellent tool that you can use to create robust marketing automation. This CRM is best suited for law firms and has features like calendar management, CRM, e-signature, document manager, etc.

It comes with a REST API, which you can use to manage all the sales, custom forms, events, signatures, contacts, notes, etc. The API uses an API key to authenticate the users. The documentation is well written and displays sample responses for each endpoint in JSON. It supports eight integrations: Zapier, Clio, Practise Panther, Rocket Matter, etc. You can check out the full list of integrations here.

Number of Integrations: 8 Github Stars: N/A

Features:

• E-signature
• Intake automation
• Create customized forms using the API as well as UI

Pega CRM API

Pega is a CRM solution from Pegasystems which provides tools to recognize customer behavior. The CRM is suitable for very large companies that need to process very high and complex inquiries.

The CRM has a REST API divided into four parts: Applications API, DevOps API, and System management API, and User management API. The API follows RAML specifications. It comes with only two integrations, which are listed here.

Number of Integrations: 2 Github Stars: N/A

SAP C4C API

SAP C4C is a cloud-based CRM solution that is easy to use and takes relatively little time to onboard. It comes with lead management, customer management, and a mobile version also.

SAP C4C comes with SOAP and OData APIs to handle contacts, user account data, teams, business, etc. The documentation is not that great and can take some time to get the hang of it. They also maintain their repository for ODATA — you can check it out here.

Github Stars: 74

Features:

• It comes with a lot of automation like sales automation, marketing automation, etc.
• Analytics and reporting

Agendize API

Agendize is a very simple CRM that lets your customers book an appointment with automated reminders. One of the best parts of this CRM is that it's so simple and easy to use.

Agendize also comes with a REST API that uses an API key for authentication and lets you manage appointments, accounts, calls, texts, emails, forms, discounts, chat, marketing, etc. They manage a Git repo where you can find some code samples in PHP to connect to the API. It supports 17 integrations, for example, Google Calendar, Office 365, Zapier, etc. You can check out the complete list of integrations here.

Number of Integrations: 17 Github Stars: 0

Centrium CRM API

Centrium CRM is a cloud-based, user-friendly CRM. It lets you manage contacts, share the history of a client, track deals and tasks, and more. Documentation is so-so, and it only comes with one PHP client. You won't find many support materials related to the API, but you can get the PHP client from here. It comes with only two integrations: MailChimp and Google Apps for Work.

Number of Integrations: 2 Github Stars: 0

Features:

• Simple to use
• Manage contacts, projects, notes, deals, tasks from a single page only.

BenchmarkONE API

BenchmarkONE (formerly Hatchbuck) lets you capture leads on your website and send marketing emails to your potential clients as well as an active client base. It is used to deliver hot leads to the sales team through a built-in CRM and effectively manage marketing campaigns.

The API of this CRM uses an API token for authentication and lets you manage contacts, settings, notes, tags, and campaigns. It can be integrated with Zapier, which allows this CRM to support 1500+ integrations. Out of the box, it supports 47 integrations. You can check out the complete list of integrations here.

Number of Integrations: 47 Github Stars: N/A

Features:

• 450+ email templates
• Supports Zapier integrations

Propeller CRM API

Propeller CRM is a powerful and minimal CRM for small teams. It primarily uses Gmail and Google Apps. It lets you manage leads, track emails, use templates, etc., all within Gmail.

The CRM comes with a REST API which can be used to send emails, schedule emails, create and manage templates, fetch analytics data, etc. The API is documented well, and it can also be integrated with Zapier, which will let you connect more than 1500+ apps. It also comes with a Python SDK to connect to the API.

Number of Integrations: 2 Github Stars: 1

Features:

• Very simple and beneficial for small teams that are dependent on Gmail.
• Funnel tracking
• Sales forecasting
• All in one dashboard

Bonus: Apideck CRM API

Here at Apideck, we provide a Unified API that aggregates multiple CRM APIs into one. Build CRM Integrations in hours – not weeks. Unified APIs simplify integration development by standardizing CRM data across different providers.

Features:

• Supports CRMs like Saleforce, HubSpot, Microsoft Dynamics, and many more.
• Get a consistent Developer-exprience.
• You only need to integrate with one API.
• Available as a REST and GraphQL API.
• Real-time synchronization without caching delays
• 190+ connectors with full CRUD support

Links:

• API reference: https://developers.apideck.com/apis/crm/reference
• Supported CRM connectors
• Other Unified APIs

AI CRM APIs in Focus

When evaluating AI capabilities across CRM APIs, focus on these differentiators:

Salesforce Agentforce: Most comprehensive but requires significant setup. Best for complex, multi-step automations.

HubSpot Breeze: Easiest implementation, focused on marketing/sales alignment. Limited customization compared to Salesforce.

Zoho Zia: Best value for SMBs. Covers basics well but lacks advanced features of enterprise platforms.

Clarify: Most innovative approach with AI-first design. Limited ecosystem compared to established players.

Integration Challenges & Considerations

OAuth 2.1 migration requires updating token management. Many providers support parallel authentication during transition. Implement token rotation now.

Webhook reliability: Assume failure. Implement webhook verification, deduplication, and replay mechanisms. Most providers now offer webhook event logs—use them.

Rate limit management: Modern CRMs use sliding windows and complexity-based limits. Implement exponential backoff and request queuing.

Compliance requirements: GDPR, CCPA, and SOC2 affect API design. Audit logs are mandatory. Document data retention policies.

The Role of Unified APIs

Direct integration with multiple CRMs creates exponential complexity. Each requires separate authentication flows, different data models, unique error handling, and ongoing version maintenance.

Unified API providers abstract this complexity. Single integration provides access to multiple CRMs with standardized data models, consistent authentication, and automatic version updates. Consider unified APIs when you hit CRM #4. Maintenance costs compound quickly beyond that point.

Final Words

Above, we covered 25 CRM APIs out there. Some of the covered CRM platforms also offer a free developer account to play around with the APIs. In general, CRMs can be very beneficial to your business, helping you grow your client base and effectively manage customer relationships. With added API connectivity, CRMs can integrate into your ecosystem very nicely.

In 2025, successful CRM connectivity requires treating integrations as core product features, not afterthoughts. Choose integration strategies based on scale requirements, not current needs.