ItaySharClaude Code
curl -fsSL https://raw.githubusercontent.com/vibe-md/vibe.md/7cb0620fbd80f9829155d8866328b58cd18d5aa7/scripts/install.sh \
| bash -s -- --skill api-check \
--agent claude-code --ref 7cb0620fbd80f9829155d8866328b58cd18d5aa7Api Check
AvailableCompare frontend API requests and consumers with backend routes to find mismatches in methods, paths, field names, response shapes, and error handling. Use for API integration reviews and debugging frontend/backend contract incompatibilities; report exact mismatches with file references.
Compares the API calls your frontend makes with the routes your backend actually serves. Your agent looks for mismatches in methods, paths, field names, response shapes and error handling, and reports each one with file and line references on both sides.
DebuggingFrontendBackend
- Claude Code
- Codex CLI
- GitHub Copilot
- Cursor
- Gemini CLI
Maintained by
The problem
A frontend and backend can disagree on a method, a path, a field name or a response shape. For example, the frontend sends customerId while the backend requires customer_id, and submitting an order fails with HTTP 400.
What it does
Follows the whole request
Traces each frontend call through shared clients, interceptors, base URLs and proxies to the backend route, validator and handler, then follows the response back to the code that uses it.
Checks four kinds of mismatch
Methods and paths, request fields (names, nesting, placement, types and required fields), response shapes (status codes, empty bodies, nesting and pagination), and error handling.
Avoids false alarms
Accounts for route prefixes and rewrites before calling a route missing. Different variable names, unused fields or routes, and types reconciled by adapters are not reported as mismatches.
Exact findings
Each finding puts the frontend request or expectation next to the backend requirement or output, with file and line references for both sides, what triggers it, what goes wrong, and a minimal fix.
Confirmed first
Confirmed mismatches come first, ordered by impact on users. Unverified concerns are listed separately with the missing evidence, and the report ends with what was inspected.
Installation
One command
Install directly into your project.
Open Terminal in your project folder, then run this command. No ZIP, moving files, or prompt needed.
- 1Open your project folder in Terminal
- 2Run the command above
- 3Reload your agent and ask to use Api Check
Works on macOS, Linux, and Windows through WSL or Git Bash. The installer checks destinations and stops if existing files conflict.
Usage examples
Type these to your agent in plain language. Here's what to expect.
you › Compare the checkout frontend requests with the backend routes.
Expected workflow
- 01Traces the checkout calls from the frontend to the matching backend routes.
- 02Compares methods, paths, request fields, response shapes and error handling.
- 03Reports each mismatch with file and line references on both sides, ordered by impact on users.
you › Review this diff for API contract drift.
Expected workflow
- 01Checks the API calls and routes in your changes.
- 02Looks at request fields, response shapes and error handling.
- 03Reports confirmed mismatches, for example the frontend sending customerId when the backend requires customer_id, so submitting an order fails with HTTP 400.
How it works
Your agent reviews the feature, endpoints or changes you name. If you name nothing, it lists the callers and routes in the project. It treats the code that actually runs as the evidence, and checks schemas, generated clients, types and tests for drift.
When the intended contract is unclear, it explains the choice instead of assuming which side must change. If it finds no mismatches, it says so only for what it inspected.
Safety and limitations
Required permissions
- Read your frontend and backend code.
- Run existing tests or isolated local checks when needed.
Limitations
- It reports findings and edits code only if you ask for fixes.
- It does not call live endpoints that change data just to check a contract.
- A clean result covers only what it inspected. Missing repositories or dynamic routes can limit what it sees.