Debug OAuth2 flows step by step — authorize URLs, code exchange, token inspection. Fix redirect_uri_mismatch in minutes — local tooling, free, no signup.
Content reviewed October 2026 · About Toolzum
Decode QR codes from uploaded images. Scan any QR code image and extract the embedded text or URL. Point it at screenshots, photos, or documents — decoded URLs and text copy out instantly. Runs locally, free, no signup.
Decode and inspect JWT tokens — view header, payload, expiration, issuer, subject, and other standard claims. Paste an HMAC secret to genuinely verify HS256/384/512 signatures — local inspection, free, no signup.
Analyze each character to see its Unicode code point and ASCII/non-ASCII status. Debug mojibake with byte-level views — free, local, no signup.
Inspect any character's Unicode code points, HTML entities, and percent-encoded bytes. Debug invisible text issues precisely — local inspection, free, no signup.
Convert TOON back to standard JSON for tooling compatibility. Return from token-efficient form losslessly — local conversion, free, no signup.
Registered redirect must match character-for-character: scheme, host, port, path, and trailing slash. Localhost ports (3000 vs 8080) cause most dev failures.
This tool does not decode tokens — it renders the authorize URL, token-exchange body, and sample response shape for a client ID and redirect URI. Decode access/ID tokens elsewhere, and never paste production secrets.
Public clients (SPA/mobile) use PKCE code_verifier; confidential servers use client_secret. Mixing them fails at the token endpoint by design.
No — debugging runs locally in your browser. Tokens never leave your device — still, use test credentials only.
OAuth Client Setup
Generate OAuth authorization URLs for Google, GitHub, Facebook, Microsoft, and LinkedIn with custom client ID, redirect URI, and scope.
JWT Inspector
Decode JWT headers and payloads instantly — inspect claims, expiry, and algorithm before trusting a token. Debug auth failures in seconds — local processing, free, no signup.