Free Online Developer Tools

Format JSON, decode JWTs, test regex, convert data and debug HTTP — 117 developer tools for real workflows. Tools run locally in your browser by default; a few require a network query.

  • Free
  • No signup
  • 117 tools
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Browse by category

Every tool grouped by what it is for. Full directory on the tools page.

JSON tools 7

JSON Formatter & Validator — Beautify, Validate, Diff and ConvertJSON minifyJSON diff

JSON format conversion 6

JSON to YAML converterYAML to JSON converterJSON to XML

YAML & TOML 3

YAML Formatter & Validator — Format YAML OnlineYAML to TOMLTOML to YAML

XML tools 2

XML Formatter — Beautify, Validate and Minify XMLSQL Formatter — Format and Beautify SQL Online

Web content authoring 2

Markdown to HTMLHTML WYSIWYG editor

JWT tools 4

JWT Decoder & Parser — Inspect Header, Payload and ExpirationBase64 Encoder & Decoder — Padding, URL-Safe, Binary-SafeDate Converter — Formats, Time Zones and ISO 8601

Base64 tools 1

Base64 to Image — Online Decode, Preview and Download

ID generators 7

UUID Generator — v4, v1, v3, v5 and NIL IDsULID Generator — Time-Ordered, Sortable IDs OnlineNano ID Generator — Short, URL-safe Unique IDs Online

Unit & data conversion 3

Unit converterTemperature converterpx / rem converter

Numbers & numerals 4

Integer base converterRoman numeral converterRMB amount in Chinese uppercase

Calculators 2

Math evaluatorPercentage Calculator

Validators & parsers 3

IBAN validator and parserPhone parser and formatterEmail Address Normalizer

Image tools 7

Image ResizerImage CompressorImage Cropper

Color tools 3

Image Color PickerColor converterColor Contrast Checker — Pass or Fail WCAG AA and AAA

QR code & data 2

QR Code generatorWiFi QR Code generator

PDF tools 5

PDF MergePDF SplitPDF Watermark

Regex tools 2

Regex Tester — JavaScript Regex Tester OnlineRegex Cheat Sheet — Complete Regular Expression Reference

DevOps & configs 5

Chmod Calculator — Unix File Permissions (755, 644, 777)Crontab Generator — Cron Expressions with Plain-English PreviewDocker Run to Compose Converter — Generate a compose Service from a Command

URL & encoding 5

URL Encoder & Decoder — Percent-Encoding, encodeURIComponent PitfallsURL parserOutlook SafeLink Decoder

HTTP tools 7

HTTP status codesHTTP status checkerHTTP headers & request methods

Network & IP 7

IPv4 Subnet CalculatorIPv4 range expanderIPv4 address converter

Hashing & crypto 7

Hash Generator — MD5, SHA-1, SHA-256 OnlineHMAC Generator — Sign Messages with SHA-256 OnlineBcrypt

Text encoding & representation 6

Text to UnicodeText to ASCII binaryText to NATO alphabet

Text transform & analysis 6

Case converterFull-width / half-width converterBatch text replacer

Text tools 2

Text diffLorem Ipsum Generator

Date & time 2

ETA CalculatorChronometer

More tools 7

Open graph meta generatorKeycode infoRandom port generator
Browse the full directory →

From the blog

Long-form guides on performance, SEO and the tooling behind this site — written for developers who build things.

Base64Base64 Encoding Guide: Padding, URLs and Binary-Safe DataHow Base64 works, why = padding breaks inside URLs, and what binary-safe really means — with online encoders and decoders for both strings and files.DevOpsDevOps Tools for Everyday Work: Cron, Permissions and Docker ComposeEveryday DevOps tasks that cost the most time — writing cron expressions, computing chmod permissions, converting docker run commands — with tools for each.DateUnix Timestamp Guide: UTC, Milliseconds and the 2038 ProblemWhat a Unix timestamp really is, why UTC and local time disagree, seconds versus milliseconds, and what the 2038 problem will do to 32-bit systems.HTTPHTTP Status Codes Guide: 2xx, 3xx, 4xx, 5xx and How to RespondWhat each HTTP status class means, why 301 and 302 behave differently, and how to handle 429 rate limiting and 503 outages on both sides of the request.JSONJSON Formatter Guide: Format, Validate and Compare JSON OnlineHow to format, validate, minify and compare JSON online — a practical guide to cleaning up API responses, spotting syntax errors and diffing config files.YAMLYAML vs JSON: Syntax Differences, Trade-offs and Parser TrapsHow YAML and JSON differ in syntax and intent, which one to pick for a given file, and the parser traps — indentation, yes/no dates — that break otherwise valid YAML.
Read all articles →
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Why DigDevBox

  • Fast: tools load in your browser with no round trip to a server.
  • Private: your input stays on your machine for every tool that can work locally.
  • No signup: no account, no email, no paywall — open a tool and use it.
  • Browser based: nothing to install, nothing to configure.

Privacy: where your data goes

Every tool runs locally in your browser by default. What you paste is not uploaded, and there is no account that could be linked to it.

These tools are the exception — they have to query a third-party service to return a result at all:

WHOIS lookupHTTP status checkerToday in history

Newest tools

New
Nano ID Generator — Short, URL-safe Unique IDs Online
Generate nanoid-style unique IDs online — URL-safe alphabet, any length, batch of up to 200, built with crypto randomness in your browser.
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Color Contrast Checker — Pass or Fail WCAG AA and AAA
Check the contrast ratio between two colours against WCAG 2.x AA and AAA thresholds for normal and large text, with a live text preview.
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Image Resizer
Resize images online to exact pixel dimensions — step-down scaling keeps detail instead of smearing it, and nothing is uploaded because it all runs in your browser.
New
Image Compressor
Compress JPEG and WebP images online to a quality level or a target file size — lossy re-encoding in your browser, so the file never leaves your machine.
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Image Cropper
Crop an image to an exact pixel region in your browser — drag the box, lock a ratio, and export at the true source resolution, not a scaled-down copy.
New
Image Color Picker
Click any pixel of an image to read its exact colour as HEX, RGB and HSL — sampled from the original file, entirely offline in your browser.
New
Favicon Generator
Turn any image into a real multi-size favicon.ico plus apple-touch-icon and 512px PNG — centre-cropped and resized in your browser, nothing uploaded.
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Images to PDF
Combine images into one PDF, each on its own page at its own size — JPEG is carried in without re-compression, and everything runs in your browser.
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CSV to JSON
Convert CSV to a JSON array with quoted fields, real newlines and duplicate-column safeguards.