# Merge

> Merge provides a unified API for 200+ integrations across HRIS, ATS, CRM, Accounting, Ticketing, File Storage, and Knowledge Base. Build once, integrate everywhere.

Merge has three products: the **Unified API** for reading and writing data across integrations, **Agent Handler** for giving AI agents secure access to third-party tools via MCP, and **Gateway** for routing LLM requests across providers.

## Instructions for AI Agents

- Always authenticate with `Authorization: Bearer <API_KEY>` and `X-Account-Token: <ACCOUNT_TOKEN>` headers
- Use the Unified API for reading and writing structured data (employees, candidates, contacts, invoices, tickets, files)
- Use Agent Handler when an AI agent needs to execute actions in third-party tools
- Use Gateway when routing LLM requests across multiple providers
- Before making POST requests, call the `/meta` endpoint to discover required fields — they vary by integration and Linked Account
- Use `modified_after` query parameter for incremental data syncing instead of full re-fetches
- Pagination is cursor-based: follow the `next` cursor in responses
- For complete section indexes, append `/llms.txt` to any section URL
- For markdown of any page, append `.md` to the page URL
- For full documentation in one file: https://docs.merge.dev/llms-full.txt

OpenAPI specs by category (append to `https://docs.merge.dev/openapi.json`):
- HRIS: `?api=b09aa0ca-693a-4876-a486-1055e9becaf4`
- ATS: `?api=ab98dbba-d4d5-47b8-b63c-7a2d3c4e41ce`
- CRM: `?api=57176b63-cbd8-42d5-9c6a-0febcc26b28f`
- Accounting: `?api=6a844f64-8d41-422d-85a8-fd9c76edb67b`
- Ticketing: `?api=471b91b1-129e-4848-931f-a9e65a6ba89b`
- File Storage: `?api=a3e19ded-5758-4da5-9c2a-f7f88b93aa65`
- Knowledge Base: `?api=d78d5e5d-d155-45d9-a15d-02fea785cc08`

## Home

- [Welcome to Merge Docs](https://docs.merge.dev/home.md): Overview of Merge's three products — Unified API, Agent Handler, and Gateway

## Getting Started

- [How Merge Works](https://docs.merge.dev/merge-unified/concepts.md): Core concepts — Merge Link, Linked Accounts, account tokens, the Unified API, and Common Models
- [Quickstart](https://docs.merge.dev/merge-unified/quickstart.md): Make your first Merge API call in under 10 minutes
- [Merge Link](https://docs.merge.dev/merge-unified/merge-link.md): Embed the drop-in UI component for end users to connect their integrations
- [Architecture Reference](https://docs.merge.dev/merge-unified/architecture.md): How Merge fits into your app
- [SDKs](https://docs.merge.dev/merge-unified/implementation/sdks.md): Official SDK installation for all supported languages

## Unified API Basics

- [Authentication](https://docs.merge.dev/merge-unified/hris/merge-api-basics/authentication.md): API key and account token authentication
- [Pagination](https://docs.merge.dev/merge-unified/hris/merge-api-basics/pagination.md): Cursor-based pagination for list endpoints
- [Rate Limits](https://docs.merge.dev/merge-unified/reading-data/rate-limits.md): Request limits by plan tier
- [Sync Frequency](https://docs.merge.dev/merge-unified/reading-data/sync-frequency.md): How often Merge syncs data from third parties
- [Webhooks](https://docs.merge.dev/merge-unified/reading-data/webhooks/overview.md): Real-time data change notifications
- [Syncing Best Practices](https://docs.merge.dev/merge-unified/reading-data/syncing-best-practices.md): Incremental syncing with modified_after

## Writing Data

- [Making Writes](https://docs.merge.dev/merge-unified/writing-data/making-writes.md): POST and PATCH requests to create and update records
- [Programmatic Writes with /meta](https://docs.merge.dev/merge-unified/writing-data/programmatic-writes.md): Discover required fields before writing
- [Related and Nested Writes](https://docs.merge.dev/merge-unified/writing-data/related-and-nested.md): Create records with relations in a single request

## Supplemental Data

- [Overview](https://docs.merge.dev/merge-unified/supplemental-data/overview.md): Ways to access data beyond Common Models
- [Passthrough Requests](https://docs.merge.dev/merge-unified/supplemental-data/passthrough.md): Proxy requests to the third-party API
- [Remote Data](https://docs.merge.dev/merge-unified/supplemental-data/remote-data.md): Get raw third-party responses alongside normalized data
- [Field Mapping](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/overview.md): Map custom fields to Common Models
- [Custom Objects](https://docs.merge.dev/merge-unified/supplemental-data/custom-objects.md): Interact with non-standard CRM objects
- [Scopes](https://docs.merge.dev/merge-unified/api-reference/scopes.md): Control which models and fields are synced

## API Categories

- [HRIS](https://docs.merge.dev/merge-unified/hris/overview.md): HR, payroll, and directory data
- [ATS](https://docs.merge.dev/merge-unified/ats/overview.md): Recruiting and applicant tracking data
- [CRM](https://docs.merge.dev/merge-unified/crm/overview.md): Sales and customer relationship data
- [Accounting](https://docs.merge.dev/merge-unified/accounting/overview.md): Invoices, payments, and financial reporting
- [Ticketing](https://docs.merge.dev/merge-unified/ticketing/overview.md): Tickets, comments, and project management
- [File Storage](https://docs.merge.dev/merge-unified/filestorage/overview.md): Files, folders, and drives
- [Knowledge Base](https://docs.merge.dev/merge-unified/knowledge-base/overview.md): Articles and knowledge content

## Full Section Indexes

For complete page listings, use these section-level indexes:
- [Unified API (all pages)](https://docs.merge.dev/merge-unified/llms.txt)
- [Agent Handler (all pages)](https://docs.merge.dev/merge-agent-handler/llms.txt)
- [Gateway (all pages)](https://docs.merge.dev/merge-gateway/llms.txt)

## Agent Handler

- [Overview](https://docs.merge.dev/merge-agent-handler/overview.md): Give AI agents secure access to third-party tools via MCP
- [Quickstart](https://docs.merge.dev/merge-agent-handler/quickstart.md): Test Agent Handler with a pre-configured tool pack
- [Key Concepts](https://docs.merge.dev/merge-agent-handler/key-concepts.md): Registered users, connectors, tools, tool packs, Link
- [MCP Integration](https://docs.merge.dev/merge-agent-handler/implementation-guides/mcp-integration.md): Connect to Agent Handler over MCP
- [Connectors](https://docs.merge.dev/merge-agent-handler/connectors.md): Browse available third-party tool connectors

## Gateway

- [Quickstart](https://docs.merge.dev/merge-gateway/quickstart.md): Send your first LLM request through Gateway
- [Routing Policies](https://docs.merge.dev/merge-gateway/guides/routing-policies/overview.md): Route requests across providers for cost, performance, or reliability
- [Tool Calling](https://docs.merge.dev/merge-gateway/guides/tool-calling.md): Let models call functions in your application
- [Cost Governance](https://docs.merge.dev/merge-gateway/guides/cost-governance.md): Budgets, spend caps, and cost optimization

## Optional

- [Postman Testing Guide](https://docs.merge.dev/merge-unified/writing-data/testing-merge-via-postman.md)
- [Sandboxes](https://docs.merge.dev/merge-unified/api-reference/sandboxes.md): Merge-hosted test environments
- [Integration Metadata](https://docs.merge.dev/merge-unified/platform-and-account-metadata/integration-metadata.md): Fetch available integrations programmatically