Developer documentation has quietly become a product category. Where teams used to throw docs into Confluence or a static site and hope for the best, the tooling has matured enough that your choice of documentation platform visibly affects how well developers can adopt your product.

Three platforms dominate the space for developer-facing docs: Mintlify, GitBook, and ReadMe. All three have added AI features in the last year, all three support the llms.txt standard for making your docs machine-readable, and all three have free tiers. So how do you actually choose?

Mintlify: The Git-Native Choice

Mintlify’s pitch is docs-as-code. Your documentation lives in a Git repository as MDX files, deploys on push, and feels like part of your codebase rather than something bolted on separately. If you’re a developer-first team that’s comfortable with pull requests for doc changes, this is a natural workflow.

The platform has built its AI features around the idea that your docs are the training data. Mintlify’s AI assistant is trained on the full content of your documentation and can answer natural language questions with citations pointing back to the source pages. This is genuinely useful for developers exploring an unfamiliar API — they can ask “how do I handle pagination?” and get a direct answer rather than trawling through pages.

Mintlify automatically generates llms.txt, which is increasingly relevant as AI coding assistants and autonomous agents need structured access to documentation. Being LLM-ready out of the box is a smart feature for teams building tools that developers will use via Claude, Copilot, or similar.

The weakness is collaboration from non-engineers. If your technical writers, PMs, or support team want to contribute to documentation without touching Git, Mintlify’s workflow creates friction. It’s designed for developers, which is a strength and a limitation simultaneously.

Pricing starts free for individual projects, with team plans from around $150/month.

GitBook: The Collaborative Workspace

GitBook’s model is broader. It’s designed for documentation that multiple types of people contribute to — engineers writing API references, technical writers editing guides, support staff adding FAQs, PMs updating changelogs. The editing interface is a rich text editor that doesn’t require Markdown knowledge, while still allowing engineers to use Markdown when they prefer it.

The AI features in GitBook lean into the collaborative angle. The AI Agent proactively scans your docs and flags gaps — pages that might be outdated, topics mentioned but not documented, or sections that lack examples. It’s more of a documentation quality assistant than a pure Q&A interface.

GitBook also generates llms.txt automatically, and it’s got solid support for large documentation projects: teams working on multi-product documentation sets, combining internal wikis with public developer docs in the same workspace.

Where GitBook sometimes frustrates developers is the feeling that it’s optimised for readability and ease of contribution over developer ergonomics. The git sync is available but it’s not the native flow the way it is in Mintlify. If your team wants to treat docs changes with the same rigour as code changes, GitBook requires more ceremony to set that up.

Free tier covers public docs. Paid plans start around $8 per user per month.

ReadMe: The API Analytics Platform

ReadMe is different from the other two in a way that matters: it’s built primarily around APIs rather than general developer documentation. If your product is an API and you want to understand how developers are actually using it, ReadMe is the one to look at.

The differentiator is the developer dashboard. ReadMe tracks API calls at the individual developer level — which endpoints they’re hitting, how often, where they’re getting errors. You can see that a specific user has tried to call the /webhooks endpoint 15 times this week but keeps getting a 422, which lets you reach out proactively before they churn. That kind of insight doesn’t exist in Mintlify or GitBook.

The interactive API explorer in ReadMe is also stronger than the alternatives. Developers can make real API calls directly from the documentation, with their own API key pre-filled, and see live responses. That reduces the “now go try this in Postman” friction that slows down API adoption.

ReadMe’s AI features are more limited than the competition, but the core product is so specifically useful for API-first businesses that it often wins anyway. If you’re a platform company where developer adoption and API usage analytics directly affect revenue, ReadMe’s visibility into that funnel is compelling.

Pricing has a free tier for small APIs, with paid plans scaling by traffic.

Which to Pick

The honest guide: if you’re a developer-first team that wants docs to live in Git alongside code, start with Mintlify. If your documentation needs contributions from across the company and you want a single workspace for all of it, GitBook is the better fit. If your core product is an API and you want analytics on how developers are using it, ReadMe is the specialist choice.

All three have matured enough that the main risk is choosing based on a feature comparison rather than your actual workflow. Think about who will be writing and maintaining the documentation — not just who will be reading it.