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To keep docs in sync with code, use a drift checker for the docs you write and a generator for docs you want rebuilt: lychee for dead links, repowise doc-drift for references to files, commands and symbols that no longer exist, Swimm or Mintlify for vendor-managed updates, and DeepWiki to generate a wiki. Most teams need a CI check first, because stale references are cheap to detect and expensive to leave.
Vendor facts below are as of November 2026, from each vendor's own pages linked in the text.
| Tool | Approach | Checks your existing Markdown | Runs in CI | Model in the loop |
|---|---|---|---|---|
| lychee | Link checker | URLs and links only | GitHub Action | No |
| Swimm | Docs tied to code, kept in sync | Vendor-managed | Not stated on the page | Not stated |
| Mintlify agent | Agent updates docs from code | Proposes updates | Automations | Yes |
| DeepWiki | Generated wiki | No | No | Yes |
repowise doc-drift | Verifies references against the tree | Yes | --check exit code | No |
Scroll the table sideways to see every column.
We build repowise, so weigh our entry accordingly. The measurements we publish about it, with their methods, are on the benchmarks page.
What documentation drift is
Documentation drift is a doc that still names a file, command, heading or function the code no longer has. It builds up silently, because nothing fails when a README goes stale. The how-to is in keeping documentation fresh.
Link checkers: lychee
lychee finds broken URLs and mail addresses. It is written in Rust, checks Markdown, HTML and plain text, is dual-licensed Apache-2.0 and MIT, and ships as a CLI, library and the lycheeverse/lychee-action GitHub Action (GitHub).
Pick lychee if you want dead external links caught in CI. It does not know that src/cli.py was renamed.
Swimm
Swimm describes its map as in sync with every commit through selective updates. That is a vendor claim; the page does not explain what triggers an update or whether it runs in CI (Swimm).
Pick Swimm if you want a commercial, managed product for living documentation and can confirm its sync behavior with the vendor.
Mintlify
Mintlify's agent can update existing documentation for new features or API changes, using code from repositories connected through its GitHub App. Updates arrive as pull requests for your team to review by default, and automations cover recurring upkeep (Mintlify docs).
Pick Mintlify if you publish a docs site on Mintlify and want an agent drafting changes.
DeepWiki
DeepWiki is Devin's generated wiki for a repository, with diagrams, summaries and source links. The free version covers public GitHub repos at deepwiki.com (Devin docs). It writes new documentation; it does not verify the docs you already maintain. Compared in repowise vs DeepWiki and DeepWiki alternatives.
repowise doc-drift
repowise doc-drift checks the paths, links, headings, commands and symbol names in your Markdown against the real tree. It reports a finding when a path no longer exists, a link target is gone, a heading was renamed or removed, a make or npm run command is no longer declared, or a symbol the line once referred to is defined nowhere. A symbol finding needs proof from git: the commit that wrote the line defined that name. It needs no model and never edits your documents (doc-drift docs).
uv tool install repowise
repowise doc-drift # everything found
repowise doc-drift --check # exit 1 in CI at 0.7 confidence or higher
Findings carry line numbers, a confidence and, where the tree shows where the reference went, a suggested replacement. Mark deliberate references with <!-- repowise-drift-ignore -->. Agents can ask which docs name a file before moving it. repowise is open source under AGPL-3.0 and self-hostable. More generators are compared in best codebase documentation tools.
Pick repowise if you want a deterministic CI gate on your own Markdown.
How to choose
- Individual developer: run
repowise doc-driftbefore a release, and lychee for links. - Open source project: both checks in CI, with a baseline if drift already exists.
- Product docs site: Mintlify or Swimm for managed updates, plus a CI check as a backstop.
- Enterprise: self-host the checker, gate pull requests, and generate a wiki separately.
FAQ
- What is documentation drift?
- Documentation drift is when docs reference files, commands, headings or functions that the code no longer has. It happens gradually as code changes without matching doc edits.
- How do I detect outdated documentation automatically?
- Run a checker in CI that resolves each reference in your docs against the repository.
repowise doc-drift --checkdoes this for paths, links, headings, commands and symbols and fails the build on high-confidence findings. - Do link checkers catch stale docs?
- Only for dead URLs. A link checker such as lychee cannot see that a doc names a function or file the code has removed.
- Can AI keep documentation up to date?
- Agents like Mintlify's can draft updates as pull requests, but they need review. A deterministic check is a good backstop.
- Does repowise doc-drift need an API key?
- No. It reads your Markdown, the file tree and git history, with no model.
