Pricing

The measurement is free. The governance around it is the paid part.

Fathohm measures comprehension debt. Comprehension debt: code no human has recently written, reviewed, or explained — measured from the record, not a survey. Reading your own number costs nothing and always will: the reading is the argument, and a number you cannot check is not one. What a team pays for is what happens after the number — declaring floors, recording decisions, and getting the history out of the product in a form you can hand to somebody else.

Free

Install the read-only GitHub App, or run the command with no account at all.

• The Map, read-only. Every file in the repository, sized by lines of code and coloured by its score, with the factor breakdown behind every one of them. No score appears anywhere in the product without the factors that produced it.
• The command line. npx fathohm reads a git clone and answers how much of the code has gone dark — no account, no network, nothing written to the repository, and never the contents of your files. The same binary simulates a departure.
• The public gallery. Comprehension-debt maps of well-known open-source repositories, with the same breakdowns, for anybody who wants to see the tool work on code they already know before pointing it at their own. Browse it.
• The weekly digest. A week’s reading — the new blind spot, the change in the number, the riskiest path — waiting in your dashboard inbox. That is where it lands today; this page will not promise you a channel that does not exist yet.
• 100 briefings a month. A briefing is the module summary generated for one file when you sit down to pay its debt: what it does, what depends on it, what breaks. The source is read transiently to write it and never stored. A hundred a month is the standing free allowance for an organisation.

Team

Everything above, plus the surfaces a team needs once the number belongs to more than one person.

• Comprehension policies. Declare a floor for a path that matters — nothing under auth/ may score below 60. Evaluation is deterministic and names the exact files and scores that breached it, never a bare pass or fail.
• The decision export. Accepted risks, paydown sessions and policy edits merge into one sorted history of who governed what, when, and why — downloadable as CSV. It is a record of human decisions about the codebase; it records nothing about how any code was written.
• The comprehension trend export. One repository’s weekly comprehension-debt series as a CSV, the same projection the dashboard draws — for the deck where somebody asks whether the number is moving.
• Ownership mapping. Your CODEOWNERS file, parsed with GitHub’s own last-match semantics, so every blind spot shows who owns it.
• Roles. Admin, member, viewer. Roles gate actions — accepting a risk, running a session, editing a floor — never what you can see. A viewer reads the same numbers an admin does.

What no plan changes

Read-only, always. The GitHub App requests read scopes only. It never writes to a repository, never executes code, and never opens a pull request — on any plan.

Your source is never stored. What is kept is metadata: paths, events, scores and summaries. Source is read transiently to write a briefing and is not persisted.

No black boxes. Every score decomposes into its factors wherever it appears, and the whole formula is published down to the constants. A number you are paying for should be one you can argue with at a specific step.