How alif10151/jwt_checking_tool works
1. What this repo is
- A small Go-based JWT utility that serves a browser UI and exposes server-side JWT operations: decode, verify, and likely token creation/validation support.
- The architecture is intentionally simple: a single Go service plus a static HTML client.
2. Runtime and top-level shape
- main.go is the application entrypoint.
- The app appears to run as a local HTTP server on port 8080, serving both the UI and the backend endpoints the UI talks to.
3. Client boundary
- client/index.html is the entire frontend surface in the tree.
- This suggests a lightweight, mostly static UI rather than a full SPA framework.
- The browser is the primary interaction point: users paste a JWT and secret, then trigger server-side processing.
4. HTTP handler layer
- handlers/ holds request-facing logic and is the boundary between the HTTP server and JWT business logic.
- handlers/cors.go indicates cross-origin support, so the service may be callable from a browser hosted on a different origin or used in a more flexible local setup.
- handlers/create_jwt.go suggests an endpoint or handler for building/signing JWTs in addition to verification-related actions.
5. JWT processing utilities
- Utility/decoder.go and Utility/verify.go contain the core JWT logic.
- This layer likely performs:
- token parsing and base64 decoding,
- extraction of header/payload claims,
- signature verification against a provided secret.
- This is the main business-logic boundary: handlers orchestrate, utilities do the JWT work.
6. Response/data shaping
- skeletons/jwt_skeletons.go likely defines reusable response shapes or example token structures used by the handlers/utilities.
- In architecture terms, this is the shared schema layer for the data passed back to the UI, such as decoded header/payload output and verification status.
7. Primary data flow
- User inputs JWT + secret in the browser.
- The client sends the request to the Go server.
- A handler receives the request, invokes the utility layer to decode and/or verify the token, and returns structured results.
- The browser renders the decoded claims, header information, and verification outcome.
8. Validation path
- The key functional path is “decode first, then verify.”
- Decoding extracts visible token data regardless of signature correctness.
- Verification uses the provided secret to confirm authenticity and integrity, returning pass/fail state to the UI.
9. Separation of concerns
- client/ handles presentation only.
- handlers/ handles HTTP concerns, request parsing, CORS, and response writing.
- Utility/ contains the JWT algorithms and parsing logic.
- skeletons/ holds shared shapes or canned data structures.
- This makes the repo easy to diagram as a three-layer flow: browser → handlers → utility.
10. Infrastructure and dependencies
- The only explicit runtime dependency is Go 1.20+.
- There is no sign of external services, databases, queues, or cloud infrastructure.
- The architecture is self-contained and local-first, which fits the “fast and lightweight” description in the README.
11. How to draw it
- Draw a single Go service box with main.go at the center.
- Inside it, show:
- HTTP server / routing,
- handler layer,
- JWT utility layer,
- shared skeleton/schema layer.
- Outside it, draw a browser client that sends token/secret input and receives decoded/verified output.
12. Important boundary to preserve
- The repo’s key architectural seam is between request handling and JWT logic.
- Keeping verification/decode logic in Utility/ prevents the UI and handler code from becoming coupled to JWT internals, which is the main design constraint visible from the file layout.
Main entry points: handlers Handlers · Utility JWT utils · index.html Browser UI · jwt_skeletons.go Skeletons
Components 10
Client
Browser UI surface
- Browser UI · Single-page HTML interface for token input and results
client/index.html
Go Service
HTTP server and JWT processing
- main.go · Starts the Go server and wires routes
main.go - HTTP server · Serves the UI and exposes API endpoints
- Handlers · Request parsing, CORS, and response writing
handlers - Create JWT · Builds or signs JWTs from request input
handlers/create_jwt.go - CORS · Cross-origin access handling
handlers/cors.go - JWT utils · Token decode and verify operations
Utility - Decode · Parses token structure and claims
Utility/decoder.go - Verify · Checks token signature and validity
Utility/verify.go - Skeletons · Reusable JWT response and example shapes
skeletons/jwt_skeletons.go
Connections 11
- Browser UI → Handlers: JWT requests · Browser submits token and secret for processing
- main.go → HTTP server: boots · Application entrypoint starts the HTTP server
- HTTP server → Browser UI: serves · Server returns the static browser interface
- HTTP server → Handlers: dispatches · Routes API calls into request handlers
- Handlers → CORS: applies · Handlers use CORS support for browser access
- Handlers → Create JWT: creates · Handler path for signing or building JWTs
- Handlers → JWT utils: calls · Handlers delegate JWT work to utility layer
- JWT utils → Decode: decodes · Token parsing and claim extraction
- JWT utils → Verify: verifies · Signature and validity checks
- Handlers → Skeletons: shapes · Handlers format responses using shared JWT structures
- Skeletons → Browser UI: renders · Structured results are presented in the UI