Free Online Developer Tools

Olutil stands for Online Utilities — a growing suite of privacy-first, browser-native web tools. This sub-site offers developer utilities that run entirely in your browser: JSON, JWT, regex, diff, Base64, URL encoding, timestamps, UUIDs, hashing, cron, SQL, .gitignore, Dockerfile, YAML, XML, HTML entities, colour, Lorem Ipsum, Markdown and QR codes — in one place. Your code and data are never uploaded. 100% Local Processing

JSON Formatter

Format, minify and validate JSON with selectable indentation.

JWT Decoder

Decode JWT header and payload. No signature check, no uploads.

Regex Tester

Test regular expressions with highlighting, groups and flags.

Diff Checker

Compare two texts and see added and removed lines.

Base64 Encoder

Encode and decode Base64 with correct UTF-8 support.

URL Encoder

Percent-encode or decode URLs and query values.

Timestamp Converter

Convert Unix timestamps to dates and back, local and UTC.

UUID Generator

Generate UUID v4 (random) or v1 (timestamp) in bulk.

Hash Generator

Compute SHA-1/256/384/512 hashes locally with Web Crypto.

Cron Parser

Explain cron expressions and list the next runs.

SQL Formatter

Beautify SQL with uppercased keywords and clause layout.

gitignore Generator

Build a .gitignore by selecting languages and editors.

Dockerfile Generator

Generate a starter Dockerfile for your stack.

YAML Formatter

Validate YAML and normalise indentation, no libraries.

XML Formatter

Pretty-print or minify XML with tag balancing.

HTML Entity Converter

Encode and decode HTML entities, named and numeric.

Color Converter

Convert colours between HEX, RGB, HSL and HSV.

Lorem Ipsum Generator

Generate Lorem Ipsum by paragraphs, sentences or words.

Markdown Preview

Render Markdown to HTML live, with no libraries.

QR Code Generator

Generate QR codes (SVG/Canvas) with a self-built encoder.

How It Works

Every tool on this site does its work locally in your browser. The code, tokens and data you paste are never sent to any server, so your work stays on your device. Pick a tool, enter your input and read, copy or print the result.

Runs 100% in your browser — no uploads, no server dependencies
Formatting, conversion, generation and analysis tools in one place
No sign-up, no accounts, no tracking pixels
Works on desktop, tablet and mobile devices

Frequently Asked Questions

Are these developer tools free?

Yes. Every tool is free to use, with no account and no sign-up. The site is supported by advertising.

Is my code or data uploaded anywhere?

No. All processing happens locally in your browser. The JSON, tokens, SQL, text and URLs you paste are never sent to a server.

Do the tools need an internet connection?

No. Once a page has loaded, the tools keep working offline because every calculation runs on your device.

Can I use the output in production?

The output is a tool result, not a guarantee. Review formatted code, SQL, Dockerfiles, QR codes and encoded values before you rely on them.