runs locally

Free online developer tools

Fast, browser-based utilities for everyday development work. Everything processes locally — nothing you paste or upload leaves your machine.

#JSON #Security #CSS #Text #Images #Converters #Date & Time

network — 0 requests

$ paste json → format

✓ done in 4ms, 0 bytes sent

$ paste text → hash sha-256

✓ done in 1ms, 0 bytes sent

$ drop image → compress

✓ done in 61ms, 0 bytes sent

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Popular tools

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#json-data

JSON Formatter

Format, validate, and beautify JSON data online.

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#development

UUID Generator

Generate RFC 4122 v4 UUIDs in bulk, instantly.

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#development

Regex Tester

Test and debug regular expressions against sample text.

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#sql

SQL Formatter

Format SQL statements for readability in the browser.

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#javascript

JavaScript Formatter

Format JavaScript snippets for readability without leaving your browser.

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Browse

Tool categories

JSON & Data Tools

6 tools

Format, validate, and transform structured data.

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Security Tools

11 tools

Hashing, encoding, and everyday crypto utilities.

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Encoding Tools

2 tools

Base64, URL, and character encoding conversions.

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Text Tools

7 tools

Diff, case conversion, counting, and cleanup.

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CSS Tools

1 tools

Generators and formatters for everyday CSS.

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Date & Time Tools

5 tools

Timestamp, timezone, and duration conversions.

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Image Tools

1 tools

Compress, convert, and inspect images.

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File Tools

1 tools

Everyday file inspection and conversion utilities.

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Development Tools

3 tools

Regex testing, formatting, and general dev utilities.

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Random & Fun

4 tools

Generate strings, numbers, dice rolls, and fun sample content.

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HTML & Web

5 tools

Parse, encode, format, and inspect web-facing data.

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Markdown

2 tools

Preview and convert Markdown content in your browser.

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SQL

1 tools

Format SQL and inspect database-oriented text snippets.

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JavaScript

1 tools

Format JavaScript snippets without leaving the browser.

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CSS & Design

8 tools

Create color palettes, gradients, and other design helpers.

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Fresh

Latest tools

JavaScript Formatter

2026-07-26

Format JavaScript snippets for readability without leaving your browser.

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SQL Formatter

2026-07-26

Format SQL statements for readability in the browser.

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Query String Parser

2026-07-25

Parse query strings into a readable object format.

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Why U5F

Built around one promise

runs locally

Runs in your browser

Tools execute client-side — no server round-trip for your data.

runs locally

No unnecessary uploads

Files and text stay on your machine unless a tool tells you otherwise.

runs locally

Fast by default

No bundlers or accounts to wait on — a tool loads and you use it.

runs locally

Free to use

Every tool on U5F is free, with no usage caps.

runs locally

Built for developers

Sane defaults, keyboard shortcuts, and copyable output everywhere.