Free, private, browser-based tools
33 tools that process everything locally in your browser. Nothing you paste is uploaded, stored or logged — open your network tab and check.
Why this is its own page. Client-side processing is a property of how a tool works, not what it does — so it lives alongside the topic categories rather than inside them. A calculator and a JWT decoder can both be private.
API URL Extractor
Unescape, extract, validate, filter and preview URLs from JSON, REST, GraphQL, Postman and Insomnia API responses.
Checklist Tracker
Turn Markdown or JSON into interactive project checklists with progress tracking, multiple lists, and one-click export.
EXIF Remover
See the hidden metadata in a photo — including where it was taken — and download a clean copy without it.
cURL to Code
Convert a cURL command into fetch, Axios, Python requests, httpx or Go — in your browser.
Age Calculator
Work out an exact age, or the span between any two dates, in years, months, days, weeks and working days.
JWT Decoder
Decode JSON Web Token headers and payloads to inspect claims without sending them anywhere.
Bill Splitter
Split a bill by what each person actually ordered, share the tip fairly, and see the fewest payments that settle everyone up.
Diff Checker
Compare two blocks of text or JSON line by line and see exactly what was added, removed or changed.
OpenAPI Viewer
Preview OpenAPI and Swagger specs as readable docs with sample responses — no Docker, no upload.
Webhook Signature Verifier
Verify Stripe, GitHub, Shopify and Slack webhook HMAC signatures locally in your browser.
Regex Tester
Test regular expressions against sample text with live match highlighting, capture groups and flags.
Timestamp Converter
Convert between Unix timestamps (seconds or milliseconds), ISO 8601, UTC and your local time — both directions.
JPG to PNG Converter
Convert JPG and JPEG images to lossless PNG right in your browser — no upload, no watermark, no queue.
Password Generator
Generate strong random passwords with control over length, symbols and ambiguous characters.
Image Compressor
Shrink JPG, PNG and WebP file sizes with a live preview of quality against bytes saved.
PNG to JPG Converter
Turn PNG images into compressed JPG files with a quality slider and a background colour for transparency.
Image Resizer
Resize images to exact pixel dimensions or a percentage, with the aspect ratio locked by default.
WebP Converter
Convert images to and from WebP to cut page weight without visible quality loss.
CSV to JSON Converter
Turn CSV or TSV into clean JSON, with header detection and type inference.
Unit Converter
Convert length, weight, temperature, area, volume, speed and data size in one place.
Word Counter
Count words, characters, sentences and paragraphs, with reading time and keyword density.
JSON Formatter
Pretty-print, minify and validate JSON with clear error messages — all client-side.
JSON to YAML Converter
Convert JSON to YAML and back, preserving key order and nesting.
UUID Generator
Generate v4 UUIDs singly or in bulk, ready to copy or download.
Colour Converter
Convert colours between HEX, RGB, HSL, HSV and CSS names, with a live swatch.
Loan Calculator
Work out monthly repayments, total interest and an amortisation schedule for any loan.
Percentage Calculator
Work out percentages, percentage change and reverse percentages without second-guessing the formula.
Base64 Encode / Decode
Encode text to Base64 or decode Base64 back to text and data URIs, privately in your browser.
Markdown to HTML
Convert Markdown into clean, semantic HTML you can paste anywhere.
Case Converter
Switch text between camelCase, snake_case, kebab-case, Title Case, UPPER and lower.
Video to GIF
Turn a short video clip into an optimised animated GIF with control over frame rate and size.
Cron Expression Generator
Build and read cron expressions in plain English, with the next run times shown.
Audio Converter
Convert audio between MP3, WAV, OGG and M4A without installing anything.
Nothing found
No tools match your search.
About these tools
What makes these tools private?
Every tool listed here runs entirely in your browser using JavaScript. Your input is processed on your own device and is never uploaded, logged or stored on a server. You can verify this by opening your browser's network tab while using one — there are no requests.
Do I need an account?
No. Every tool on this page is free and requires no signup, login or installation.
Can I use them offline?
Once a tool page has loaded, the processing itself needs no network connection. Reloading the page does still require one.
Are all tools on the site browser-based?
Not necessarily. This site is a broad catalogue of 36 mini apps, and this page lists the subset that is both free and fully client-side. Any tool that needs a server is labelled as such on its own page.