Student Toolkit

Count exact LLM tokens for GPT, Claude and Gemini prompts.

Pretty-print, minify, sort and deduplicate JSON Lines files.

Convert JSON Lines to a JSON array and back again.

Check that a model's JSON reply matches your JSON Schema.

Convert function-calling schemas between OpenAI, Anthropic, Gemini and MCP.

Convert between OpenAI chat, ShareGPT, Alpaca and prompt/completion.

Pretty-print and beautify JSON with custom indentation.

Convert JSON into well-formed, indented XML.

Convert JSON documents to clean, readable YAML.

Flatten a JSON array of objects into a CSV spreadsheet.

Count words, characters, sentences, and reading time.

Count characters and bytes with limit presets.

Convert text between 11 different letter cases.

Generate placeholder text for mockups and designs.

Analyze readability with Flesch score and syllable stats.

Split delimited text into aligned columns and re-join it.

Prettify and align Markdown tables with column alignment.

Obfuscate text with ROT13, zero-width spaces, or leetspeak.

Generate lorem ipsum text wrapped in HTML tags.

Count how often each word appears in your text.

Hard wrap text to a fixed column width.

Inspect code points, categories, and byte lengths of every character.

Turn newline-separated lines into a quoted, comma-joined string.

Beautify and indent messy HTML markup.

Beautify or minify CSS with safe string handling.

Design linear, radial, and conic gradients visually.

Visually build flexbox layouts and copy the CSS.

Design CSS grid layouts with live preview.

Translate common Tailwind utility classes into plain CSS.

Convert between px, rem, em, %, pt, vw, and vh.

Design named grid-template-areas visually.

Convert images between PNG, JPEG, and WebP in your browser.

Convert images to Base64 data URLs and back again.

Convert any image into ASCII text art in your browser.

Convert SVG files to PNG images at any scale.

Resize and convert many images at once in your browser.

Combine photos into a grid collage and download a PNG.

Trace PNG or JPG images into clean, scalable SVG paths.

Convert iPhone HEIC/HEIF photos to JPG or PNG in your browser.

Convert images to and from AVIF with quality control.

Convert WebP images to JPG or PNG, or encode images as WebP.

Analyze keyword frequency and density in your text.

Convert between CSV and JSON with delimiter and header options.

Convert YAML to JSON and JSON to YAML.

Convert XML to JSON and JSON to XML using the browser's DOMParser.

Convert Markdown to HTML with a live preview.

Convert numbers between binary, octal, decimal, hex, and custom bases.

Convert length, weight, temperature, area, volume, speed, and data-size units.

Convert CSV into a Markdown or HTML table with alignment options.

Parse simple SQL INSERT INTO statements into JSON rows.

Convert text to binary or octal codes and back.

Convert between numbers and Roman numerals.

Convert CSV data into well-formed XML with custom tag names.

Convert TOML configuration files to JSON and back.

Convert between milliseconds, seconds, minutes, hours, days, and weeks.

Convert bytes, KB/MB/GB/TB with binary (KiB/MiB) or decimal units.

Convert between base64/data URI text and image previews.

Spell numbers out in words or format them as currency, ordinals and locale text.

Convert HTML markup into clean Markdown syntax.

Generate SQL INSERT statements from CSV data.

Convert between spreadsheet column numbers and letters.

Convert INI config files to JSON and back.

Convert nested JSON config into .env variables.

Convert Markdown content into a JSX React component.

Beautify and normalize YAML with a hand-written parser.

Beautify XML and validate well-formedness using DOMParser.

Spell out text using the NATO phonetic alphabet.

Turn any JSON document into a ready-to-paste PHP array.

Convert between .proto-described binary payloads and JSON.

Turn JSON into Swift structs that conform to Codable.

Convert Apple property lists to JSON and back.

Convert Localizable.strings files to JSON and back.

Convert Android string resources to JSON and back.

Convert certificates and keys between PEM and DER encoding.

Convert JSON Web Keys to PEM and PEM keys back to JWK.

Convert between Unix timestamps and human-readable dates.

Format a date using custom patterns and Intl presets.

Convert a datetime across multiple IANA timezones at once.

Convert dates and durations to and from ISO 8601 format.

Count business days between two dates, excluding holidays.

Live countdown to any date and time.

Convert a list of Unix timestamps to readable dates in bulk.

Precision stopwatch with laps plus a countdown timer with alarm.

Convert colors between HEX, RGB, HSL, HWB, OKLCH and CMYK.

Extract and normalize colors from CSS gradients or lists.

Turn a hex color into SwiftUI, UIKit and asset catalog code.

Convert IPv4 to decimal/hex/binary, and expand or compress IPv6.

Convert between URL query strings and JSON, with nested bracket support.

Convert internationalised domain names to punycode and back.

Convert between decimal, scientific, and engineering notation.

Calculate a discounted price plus sales tax and total savings.

Convert .env files to JSON, YAML, or shell exports.

Convert identifiers between camelCase, snake_case, kebab-case, and more.

Minify or beautify JavaScript, CSS, HTML, JSON, XML and SQL.

Convert a curl command into JavaScript fetch() code.

Convert a JS object literal into strict, valid JSON.

Format and indent SQL queries for readability.

Format and indent GraphQL queries and mutations.

Convert indentation between tabs and spaces.

Convert install/run/exec commands between npm, yarn, pnpm and bun.

Build ffmpeg commands for video and audio with explained flags.

Run real ffmpeg commands on your video, audio or image — no install.

Validate IBANs with the mod-97 checksum and country length rules.

Convert dp, px and sp across every Android density bucket.

Create an .editorconfig file with per-language overrides.

Count code, comment and blank lines in any source file.

Convert between PHP serialize() format and JSON.

Convert HTML markup into clean React/JSX component code.

Convert Maven POM XML to Gradle Kotlin DSL and back.

Convert Java .properties files to JSON and back, with nested keys.

Resize or crop video to 9:16, 1:1, 4:5 and other social presets.

Convert video between MP4 and WebM with resolution control.

Turn any part of a video into a looping animated GIF.

Convert an animated GIF into a far smaller MP4 or WebM video.

Render Markdown into a printable page and save it as a PDF.

Turn pasted HTML into a print-ready page you can save as PDF.

Combine JPG, PNG or WebP images into a single PDF, offline.

Convert PDF pages to PNG, JPEG or WebP images at any resolution.

Parse an OpenSSH public key and show its SHA256/MD5 fingerprints.