Getting started

This page takes you from nothing to a first report in a couple of minutes.

Requirements

• Node.js 22.18 or newer. edgefit runs on Node even when the project you check targets Bun or Deno.
• Your project's dependencies installed, so node_modules exists. edgefit reads the packages you actually ship.

Try it without installing

npx edgefit check

If your project has a wrangler.jsonc, wrangler.json or wrangler.toml, that is all you need. edgefit reads the entry point from wrangler's main, along with the compatibility date and flags.

For any other project, point it at the entry file:

npx edgefit check --entry src/index.ts

Install it in the project

Installing edgefit as a dev dependency pins the version, which also pins the compatibility data, and gives your config file types.

npm

npm install --save-dev edgefit

pnpm

pnpm add --save-dev edgefit

yarn

yarn add --dev edgefit

bun

bun add --dev edgefit

Then add a script:

{
  "scripts": {
    "edgefit": "edgefit check"
  }
}

Your first check

Run the check

npx edgefit check --entry src/index.ts

Read the header

edgefit · workerd (Cloudflare Workers)
  entry src/index.ts · 5 modules · conditions workerd, worker, browser
  data workers-nodejs-compat-matrix@ee58120 (workerd 1.20260929.1), ...
  settings compatibility_date 2026-09-29, flags: nodejs_compat (from wrangler.jsonc)

The header says which target was checked, how many modules were reached, which export conditions were used, which data the results come from, and where the runtime settings were read from.

Read the findings

error    unsupported  node:fs.watch  (workerd)
       file watching is not implemented; throws ERR_UNSUPPORTED_OPERATION
       chokidar@4.0.1  node_modules/chokidar/index.js:5:13
       via src/index.ts > src/dev/reload.ts > chokidar

warning  unknown  require(<expression>)  (workerd)
       cannot be checked statically: the module name is computed at runtime
       pg-lite@0.3.0  node_modules/pg-lite/lib/index.js:12:10
       via src/index.ts > pg-lite

1 error, 1 warning

Each finding starts with its level and category. The via line is the import chain: follow it to see why a package is in your graph at all.

Fix or accept

Remove the import that pulls the package in, swap it for one that supports the runtime, or, if the code path never runs in production, ignore it with a reason.

Check more than one runtime

Pass --target more than once. The same entry is used for every target.

npx edgefit check --target workerd --target bun --target deno

To see the results side by side, use edgefit compare.

Exit codes

Code	Meaning
0	No error-level findings
1	At least one error-level finding
2	Invalid input, or a project that could not be resolved

Warnings never fail the run. You can raise or lower any category with levels.

Next

• Reading findings explains every category.
• Configuration covers edgefit.config.ts.
• Pull request checks runs edgefit on every pull request.