Calculate screen width and height from diagonal size and aspect ratio. Convert between inches and centimeters for displays, TVs, and monitors with instant dimension calculations.

Calculate DPI (dots per inch), image dimensions, and print sizes. Convert between pixels and physical dimensions for printing and displays.

Convert seconds to HH:MM:SS time format instantly with precise calculations and easy-to-read formatting.

Calculate the information-theoretic bit entropy of any password or API key. Detects character set pools automatically, shows the total number of possible combinations, and estimates crack time across five attack scenarios from rate-limited web logins to GPU cracking clusters.

Generate time-based one-time passwords from a TOTP secret key. Enter your base32 secret, choose a period and digit length, and get the current and next codes with a live countdown timer. Useful for testing and debugging 2FA integrations.

Format, validate, and inspect JSON Lines (JSONL) and NDJSON files. Validates each line individually, reports parse errors by line number, outputs compact JSONL or a pretty-print preview, and lets you download the cleaned file.

Check TLS protocol version compatibility and cipher suite strength ratings against current best practices. Supports IANA and OpenSSL cipher names — rates each suite as Strong, Weak, or Deprecated and explains why.

Generate Zod validation schema code from a JSON sample object. Infers z.string(), z.number(), z.boolean(), z.array(), z.object(), and z.null() types automatically. Handles nested objects, arrays of objects with optional field detection, and outputs copy-ready TypeScript with import and z.infer type alias.

Generate RFC 7636 PKCE code verifier and challenge pairs for OAuth 2.0 authorization code flow. Choose verifier length, get the SHA-256 code challenge, and see exactly where each value goes in the auth URL and token exchange request.

Convert API change descriptions into structured Keep-a-Changelog format. Enter a version, date, and one change per line prefixed with its type (added, changed, deprecated, removed, fixed, or security). The tool instantly groups them into the canonical section order and outputs a ready-to-paste CHANGELOG.md block. Supports four real-world presets for REST API releases, breaking changes, patch releases, and unreleased work. Free and runs entirely in your browser.

Convert OpenAPI 3.x JSON or YAML specs into a ready-to-import Postman Collection v2.1. Paths, methods, parameters, request bodies, and tags are all mapped automatically.

Validate and inspect OAuth tokens in your browser. Decode JWT access tokens and ID tokens to view claims, scopes, and expiry. Analyse opaque tokens for entropy and format. Free and private.

Generate Cache-Control, Vary, and ETag headers for web and API responses. Select a caching strategy (public, private, no-cache, no-store), set browser and CDN TTLs, and configure advanced directives like stale-while-revalidate. Outputs ready-to-use snippets for nginx, Express.js, and Apache.

Test HTTP API endpoints directly in your browser. Make GET, POST, PUT, PATCH, and DELETE requests with custom headers and request bodies. View status codes, response headers, and pretty-printed JSON responses — all client-side, no server proxy.

Compare two API response payloads and highlight added, removed, and changed fields. Paste any two JSON responses to get an instant field-level diff with color-coded changes and a summary count.

Configure exponential backoff parameters and preview the full retry schedule for webhook delivery. Enter max attempts, initial delay, multiplier, jitter, and a max delay cap to instantly see each retry timestamp, cumulative elapsed time, jitter range, and which delays hit the cap. Supports presets for standard, aggressive, conservative, Stripe-style, and fixed-interval retry policies. Free and runs entirely in your browser.