John's page of free tools. Enjoy!

Practice basic arithmetic with timed, configurable drills.

Combine every file in a ZIP into a single text document.

A simple traffic light simulation.

Client-side PDF merging, editing, annotation, and splitting — nothing leaves your browser.

Open an ebook from Gutenberg or your library and read it here, with a contents list and adjustable text size.

Open .doc and .docx files, make quick edits with a basic toolbar, then download as .doc or HTML — all in your browser.

Paste a chunk of a web page and get clean Markdown back — headings, links, lists, code and tables.

Write Markdown with a live HTML preview, then copy or export to HTML or PDF.

Pull the text out of an image or scanned PDF — the recognition runs in your browser, so the file is never uploaded.

Open an .ics invitation or calendar export and actually read it — times, places, attendees and repeats.

Count words and characters, transform case, sort and dedupe lines, and generate placeholder text.

Cut a clip out of an audio file by dragging on the waveform, with optional fades — exports at full quality.

Resize, crop, compress, and convert images — and strip EXIF metadata — entirely in your browser.

Drop a .ttf, .otf or .woff to see its metrics, embedded licence and every glyph it contains.

Pick colors, build harmonious palettes, convert HEX/RGB/HSL, and check WCAG contrast.

Map a GPX, KML or TCX track, see distance, ascent and duration, and export it as GeoJSON.

Generate QR codes for links, Wi-Fi, and contacts — with colors and a logo — and scan codes from images.

Make EAN, UPC, Code 128 and ten more barcode formats, and export them as sharp SVG or PNG for labels.

Strip the metadata and rounding cruft out of an exported SVG, with a before-and-after preview.

Write a flowchart, sequence or ER diagram as text and watch it draw itself — then export SVG or PNG.

Open an STL, OBJ, PLY or GLTF, orbit around it, check the triangle count, and save a picture.

A simple whiteboard for diagrams and planning — drop boxes, ellipses, and sticky notes, then connect them with arrows.

Build a ZIP from a pile of files, or open one and pull individual files out — without installing anything.

Open a big CSV without Excel mangling it — check it, convert to JSON, and chart a column.

Convert between JSON, YAML and XML in either direction, with a live preview and a one-click swap.

Format, minify, validate, and sort JSON — with key sorting and instant size feedback.

Run real SQLite queries against a database file or a CSV — without uploading your data anywhere.

Convert length, mass, temperature, data, and more — plus binary, octal, decimal, and hex.

Tidy JavaScript, TypeScript, CSS, HTML, JSON, YAML and Markdown with Prettier — without pasting code into someone else's server.

Turn a cron expression into plain English, break it into fields, and see the next five times it fires.

Compare two blocks of text or JSON side by side, with highlighted additions and removals.

Read a token's header, claims and expiry — and check an HMAC signature — without it leaving the tab.

Generate UUID v4/v7, Nano IDs, and hex tokens in bulk — cryptographically random.

Write LaTeX and get the equation back as SVG, PNG or MathML you can paste straight into Word.

Timed typing practice with live WPM, accuracy, and a per-key error heatmap.

My first web-based game project.

A Windows auto-clicker written for my son.