Everything in the catalog

Renders Markdown containing LaTeX equations with KaTeX, showing the HTML output too.

Shows when web APIs first shipped in each browser, using MDN's compatibility data.

Breaks a millisecond count into seconds, minutes, hours, days and weeks, plus a plain-English duration.

Animated bar chart of Elo ratings over time that you can feed with your own JSON.

Reads an MP3 file's ID3 tags, cover art and encoding details without uploading it.

Spells out letters and numbers using the NATO phonetic alphabet for clear radio-style reading.

Plays notes on a small keyboard to show that an octave is a 2:1 frequency ratio.

Paste a draft and Claude marks words that can be cut without changing the meaning.

Records a voice message in the browser and submits it to an OpenAI audio model using your API key.

Sends prompts with different structures to OpenAI and shows how many tokens were served from cache.

Opens a realtime voice conversation with an OpenAI model over WebRTC, with optional document context.

Text editor that turns long pasted text or files into attachments below the draft.

Shows two PDFs page by page with a third panel marking pixel differences in red.

Opens a PDF from a URL with page navigation and zoom, and keeps the current view in the address bar.

Rescales up to four percentages so they total 100 after you tick off the ones to ignore.

Arranges photos on A4 pages in a grid you configure, in portrait or landscape, ready to print.

Turns PHP serialized strings into readable JSON.

Extracts package pins from a Pipfile.lock and outputs them in other formats.

A focus timer with goal setting, preset lengths from 5 to 60 minutes and saved session history.

Enter a text prompt, choose a GPT-4o audio model and listen to the spoken reply.

Compares two released versions of a Python package by fetching their archives and showing the file differences.

Checks pasted requirements or pyproject dependencies against the OSV.dev database and lists known vulnerabilities.

Makes QR codes for links, text or WiFi logins, with choice of module style, size and colors.

Decodes QR codes from an uploaded image, pasted picture or live webcam feed.