A new category has grown up in the last year: tools that notice a code change and update the docs for you. They sound alike on their homepages. They work very differently once you look at the details.
We make DocFit, so read our pick with that in mind. To keep this useful anyway, every claim about another product below comes from that product’s own documentation or pricing page, as listed on October 16, 2026. Where a vendor doesn’t document something, we say “not documented” rather than guess.
What we compared
Four questions decide whether a tool keeps docs current without creating new work:
- What starts an update? A merged pull request reflects what actually shipped. An open pull request can still change in review, so docs written from it can describe code that never merges.
- Can your docs stay where they are? Some tools only edit docs hosted on their own platform. If your docs are in Docusaurus, MkDocs or a separate repository, that rules them out, or means a migration.
- Is the result checked before a person reviews it? A docs change that breaks the build or a link is worse than no change.
- What does it cost a small team?
At a glance
| Tool | What starts an update | Where your docs can live | Checked before review | Starting price |
|---|---|---|---|---|
| DocFit | Merged PR, plus its linked ticket | Mintlify, Docusaurus, Redocly/OpenAPI, MkDocs, any Markdown folder; same repo or separate | Your docs build and lint scripts, links, Redocly lint | Free; Team $49/mo |
| Promptless | Open PR by default (merge optional), Slack, Jira | Several platforms, including Mintlify, Docusaurus, Fern and ReadMe | Not described in its docs | $500/mo |
| Mintlify Automations | Merged PR or a schedule | Mintlify only | Mintlify build check | $450/mo, billed yearly |
| ReadMe GitHub AI Writer | Open PR, diff only | ReadMe only | Not documented | $250/mo, billed yearly |
| EkLine | Merged PR | Several platforms, including Mintlify, GitBook, ReadMe and Docusaurus | Not documented for drafted updates | Free; Pro $50/mo plus token usage |
| Dosu | Open PR | Its own knowledge library (Git, Notion, Confluence) | Not documented | Free; Pro $16/mo |
| GitBook Agent | Support tickets and GitHub issues; no code trigger documented | GitBook only | Not documented | Free with limits; $65/site/mo plus $12/user |
| Fern Agent | On request, or a schedule | Fern docs | Not documented | Free tier |
| Swimm | Open PR | Swimm’s own .swm docs |
Checks snippets against code | Contact sales |
| DeepWiki | Generates its own wiki | Doesn’t edit your docs | Not applicable | Free for public repos |
1. DocFit
DocFit is a GitHub App built for one job: when a pull request merges, update the docs it made wrong.
- It starts from what shipped. DocFit runs on the merge, and reads the whole change: the PR description, commits, review comments and the linked Jira or GitHub issue. The ticket usually explains why, which is what the docs need.
- Your docs stay where they are. Mintlify, Docusaurus, Redocly, MkDocs, Nextra, VitePress or a plain Markdown folder, in the same repository or a separate one. There’s nothing to migrate, and edits follow your framework’s components and nav.
- It finds the pages nobody remembers. Changed operations in your OpenAPI spec, and names from the diff (routes, enums, environment variables, CLI flags) matched against every page, not just the obvious one.
- Every PR is checked before you see it. Your repo’s own docs build and lint scripts (Vale, markdownlint or Spectral, if they call them), internal links, and Redocly lint on the spec. Low confidence or a failed check opens a draft instead of a ready PR.
- You stay in control. DocFit opens a normal pull request on a
docfit/branch with a reason for every page it touched. It never merges anything. - It’s priced for small teams. Free for public repositories and one private repo. Team is $49 a month for up to five private repos, where the platform agents below start at $250 to $500 a month.
For a real example, see the code PR and the docs PR DocFit opened for it, in a separate docs repository.
2. Promptless
Promptless drafts docs updates from pull requests, Slack and Teams conversations, and Jira ticket changes, and works with several docs platforms. That breadth is its strength.
Two things to know. Its GitHub trigger fires when a PR is opened by default; triggering on merge is an option you set. And plans start at $500 a month for up to 200 pages, rising with page count to $4,000 a month for 5,000 pages. Its own documentation doesn’t describe automated checks such as builds or link checks before a suggestion reaches you.
3. Mintlify Automations
If your docs are on Mintlify, Automations can run when a pull request merges in a connected code repository, or on a schedule, and open a PR in your Mintlify project. Its agent runs Mintlify’s CLI checks so the docs still build.
The catch is scope and cost. It works on Mintlify projects only, and Automations come with the Pro plan at $450 a month billed yearly ($540 monthly). Each run that updates docs uses 250 credits, and Pro includes 10,000 credits a month: about 40 updating runs before extra credits at $0.01 each, or $2.50 a run.
4. ReadMe GitHub AI Writer
ReadMe’s GitHub AI Writer drafts changes when a pull request is opened in a connected repository, on a review branch in ReadMe, and comments on the PR with a preview.
It analyses the diff only; its documentation doesn’t mention reading linked tickets. It updates guides in ReadMe projects only, and it’s part of the Pro plan at $250 a month billed yearly.
5. EkLine
EkLine is the closest to DocFit in approach: merged pull requests become drafted updates, delivered as pull requests, across several docs platforms.
The difference is in the checking. EkLine’s pricing page lists a link checker, style rules and Vale or markdownlint as separate features; it doesn’t document running them on the drafted updates before you review. Pro is $50 a month plus token usage, so the bill moves with how much it writes.
6. Dosu
Dosu keeps a Markdown knowledge base current for teams and coding agents. It reviews a pull request while it’s open and posts a “knowledge review” comment with suggested edits to accept or decline; accepted edits to docs in Git become a separate PR.
It’s built around its own knowledge library and needs an existing set of documents to compare against. It’s inexpensive (Pro is $16 a month), and a good fit for internal knowledge. It documents no build or link checks.
7. GitBook Agent
GitBook Agent can generate change requests from connected sources such as support tools, GitHub issues and discussions. Code repositories aren’t listed as a source, and that feature is labelled beta. Triggering from GitHub through “channels” is still rolling out by early access.
It edits GitBook spaces only. Paid plans start at $65 per site per month plus $12 per user, billed yearly.
8. Fern Agent
Fern Agent opens a docs PR when you ask it in Slack or the dashboard (“document PR #123”), or runs a prompt on a schedule, at most once every 20 hours. No trigger on a pull request opening or merging is documented. It’s built around Fern docs and supports GitHub only.
9. Swimm
Swimm keeps internal, code-coupled documentation in sync: its GitHub App flags open PRs that affect Swimm docs and can update small things like renamed variables. It only edits Swimm’s own .swm files, so it isn’t for customer-facing docs sites, and the company now focuses on legacy code modernization. Pricing is by lines of code, through sales.
10. DeepWiki
DeepWiki, from Cognition, generates a wiki from a repository; it’s free for public repos at deepwiki.com. It’s a useful way to explore unfamiliar code, but it doesn’t update your existing docs: it produces its own wiki alongside them.
How to choose
- Your docs are on Mintlify, ReadMe or GitBook and staying there: that platform’s own agent is the least setup, as long as its trigger and price fit.
- You want docs updated from Slack conversations as well as code: Promptless covers more sources, at a higher price.
- You want internal knowledge kept current, not a public docs site: look at Dosu or Swimm.
- Your docs live in your own repository, in any framework, and you want every merge turned into a checked docs PR you review: that’s what we built DocFit for. One honest limit: DocFit works with GitHub today.
See how DocFit works, or start free below and see what it would have changed in your docs for your last few merged pull requests.