Development & programming

Generate random browser user agent strings. Filter by browser type and operating system.

Password-protect and unlock URLs entirely in your browser using AES-GCM encryption, compatible with the Link Lock link format.

Validate SPDX license identifiers, check for deprecated licenses, and browse the full list of standard open-source license IDs.

Test and measure your monitor refresh rate in Hz using requestAnimationFrame

Check how old a domain name is by looking up its WHOIS registration date. See the exact age in years, months, and days, along with registrar and expiry details.

Check when a domain name will expire, including days remaining, registrar, and registration dates.

Check whether a domain name is available to register or already taken. Runs a live WHOIS lookup and shows registrar, creation, and expiry details when the domain is registered.

Identify the web server software running on a host via a GET request to its index page.

Preview how a URL will look when shared on Facebook, Twitter/X, LinkedIn and other platforms by inspecting its Open Graph and Twitter Card meta tags.

Fetch an RSS or Atom feed by URL and preview its title, description, and items.

Look up RDAP registration data for any domain, including registrar, registrant, nameservers, and expiry date.

Generate ready-to-use, well-structured prompts for chat AI, image generation, code, or writing assistants from a simple description.

Convert GitHub Copilot AI credits to US dollars and back. GitHub bills Copilot usage in AI credits, where 1 AI credit equals $0.01 USD.

Generate cURL commands for OpenAI-compatible API endpoints. Configure base URL, endpoint, model, prompt, temperature, and other parameters for chat, completions, and embeddings requests.

Create a free online kanban board with drag and drop columns and cards. Rename columns, reorder cards, and import or export your board as JSON.

Run SQL queries against a SQLite database right in your browser. Create tables, import or export .sqlite and .db files, and browse the results in a sortable table.

Generate the daemon.json settings that control which subnets Docker uses: default-address-pools and the docker0 bridge address (bip). See how many networks fit into your ranges and check for clashes.

Check how big a JSON Web Token is in bytes. See the size of the header, payload, and signature, find the largest claims, and test the token against HTTP header limits of nginx, Apache, Node.js, and more.

Edit JSON as a tree. Change values, rename keys, and add or remove objects, arrays, and items with a click, while the JSON text stays valid and up to date.

Run JavaScript in your browser and see the console output right away. Supports async code and top-level await, shows errors, and lets you stop a script that never ends.

Run TypeScript in your browser and see the console output right away. Types are removed without a build step, and enums, decorators, and top-level await all work.

See everything your browser reveals about your system: browser and OS version, CPU, GPU, memory, screen, network, time zone, storage, media formats, permissions, and supported web APIs.

Edit a Cookie or Set-Cookie header in a form. Change names, values, and attributes like Domain, Expires, SameSite, and Secure, and get the updated string with warnings for common mistakes.

Build a compose.yaml for Uptime Kuma. Choose the image version and variant, ports, data location, Docker monitoring, and a SQLite or MariaDB database, and get a file that is ready to run.