I built a CLI that reads your broken CI log and tells you why it failed in plain English

Every developer knows the feeling.

Your CI pipeline fails. You open the log. There are 300 lines of noise — progress bars, timestamps, test runner output — and somewhere buried in there is the one line that actually matters.

I got tired of hunting for it. So I built ci-why.

What it does

You pipe your failed CI log into it, and it tells you:

• 
  WHY the build failed (in one sentence)


• 
  Which exact line caused it


• 
  What to fix
  

cat build.log | ci-why

That's it. You get back something like this:

──────────────────────────────────────────────────

  WHY

  The authentication service is returning null for the token field

  instead of a valid token string, causing the test assertion to fail.



  FAILING LINE

  src/services/auth.test.ts:63



  SUGGESTED FIX

  Check authService.login() in auth.ts — it's returning {"token": null}

  for valid credentials. The login logic needs fixing, not the test.

──────────────────────────────────────────────────

Instead of reading 300 lines, you read 8.

How to install it

npm install -g ci-why

You'll need an Anthropic API key (free to get at console.anthropic.com). Set it once:

export ANTHROPIC_API_KEY=your-key-here

Then use it however fits your workflow:

# Pipe from anywhere

cat build.log | ci-why



# Point at a file

ci-why ./logs/build.log

How it works

ci-why does four things under the hood:

1. 
   Strips the noise — removes ANSI escape codes, progress bars, timestamps, and anything else that clutters CI logs


2. 
   Finds the signal — pulls out lines containing errors, exceptions, and failures, plus the last section of the log


3. 
   Asks Claude — sends the cleaned excerpt to the Anthropic API with a tight prompt asking for: why, where, and how to fix it


4. 
   Prints the result — formats it into the clean coloured output you saw above

The whole thing uses claude-haiku which is fast and cheap. A typical analysis costs less than a fraction of a cent.

It's free and open source

ci-why is completely free. You bring your own Anthropic API key so there's no subscription, no account, no billing through me.

The code is on GitHub: github.com/ciwhy-tool/ci-why

A paid cloud tier with GitHub Actions integration and team features is planned for the future — but the core CLI will always be free and open source.

What's coming next

• GitHub Actions integration (auto-comment on PRs with the failure explanation)


• Support for more log formats (pytest, Go test, Cargo, Maven)


• 
  --json flag for piping output into other tools

Try it and let me know what you think

If you try ci-why and hit a bug, have a suggestion, or just want to say it helped — drop a comment below or open an issue on GitHub. This is v0.1 and real feedback from real developers is exactly what I need to make it better.

npm install -g ci-why