Early access

A light in the dark for developers.

Free developer tools — no sign-up, no tracking. Most tools run entirely in your browser. Open any tool and start working.

HTTP & Web

HTTP Header Analyzer

Paste raw HTTP response headers and check for missing or misconfigured security headers: CSP, HSTS, X-Frame-Options, and more.

CORS Tester

Send a real preflight and actual request to any URL and diagnose the CORS configuration. Identifies missing or misconfigured Allow-Origin, methods, and credentials headers.

API Request Builder

Build and send HTTP requests from your browser. Set method, headers, and body, then see the full response with status, headers, and body. Server-side proxy avoids CORS restrictions.

Redirect Checker

Follow HTTP redirect chains for any URL. See every hop with status code, Location header, and timing. Debug redirect loops, broken chains, and final destinations.

Webhook Inbox

Create a temporary endpoint, receive webhooks, and inspect payloads in real time.

Data & Formats

Data Format Converter

Convert between JSON, YAML, TOML, CSV, XML, and SQL. Auto-validates input and prettifies with one click.

Markdown to HTML

Convert Markdown to sanitized HTML with a live side-by-side preview. Copy the HTML fragment or download a complete file.

Diff Viewer

Paste two blocks of text to instantly see a visual unified diff with additions, deletions, and a copyable raw patch.

SVG to PNG Converter

Paste SVG markup and download a PNG at any resolution. Set custom width and height — renders via browser Canvas.

JSON Schema Generator + Validator

Paste sample JSON to instantly generate a draft-07 JSON Schema. Switch to Validate mode to check any JSON against a schema. Runs entirely in your browser.

SEO & Meta

UTM Builder

Build UTM-tagged URLs for campaign tracking. Fill in source, medium, and campaign to generate a live tracking link. Paste a pre-tagged URL to extract and edit its parameters.

Robots.txt + Sitemap Validator

Validate your robots.txt and sitemap.xml by URL or paste. Parses user-agent groups, Disallow/Allow rules, crawl directives, and sitemap URL counts.

Open Graph / Social Card Preview

Extract Open Graph and Twitter Card meta tags from any URL or HTML snippet. See a visual preview of how your page appears when shared on social platforms.

Security & Auth

JWT Decoder

Decode and inspect JWT header, payload, and standard claims. Fetch the matching public JWK via the token's jku URL.

Regex Tester

Test JavaScript regular expressions against multiple strings with live matching, capture group inspection, and match indices.

SSL Certificate Monitor

Check any domain's SSL certificate expiry date, issuer, Subject Alternative Names, and SHA-256 fingerprint. Never get caught by a silent expiry.

Generators

UUID / ULID / NanoID Generator

Generate UUID v4, UUID v7, ULID, and NanoID identifiers. Bulk-generate up to 100 at a time.

Cron Expression Builder

Build and validate cron expressions with a visual field editor. Preview the next 10 scheduled run times in UTC.

AI for Marketing

Turn your project description into polished launch copy for Product Hunt, Twitter, LinkedIn, Reddit, and GitHub.

Pro tools coming

Webhook Inbox

Receive, inspect, and replay webhook payloads from any service.

Cron / Heartbeat Monitor

Get alerted when a scheduled job silently fails to run.

SSL Cert Watchlist

Monitor multiple domains and get notified before any certificate expires.

Mock API Sandbox

Persistent mock endpoints that return whatever you configure.

One Pro plan · €12/mo · Free tools are always free.

View roadmap