New in 2.7.0 Mermaid diagrams, time zones and a sandboxed playground

Free, OfflineDeveloper Toolkit

Format JSON, decode JWTs, compare text, and more—all in one desktop app. Works completely offline. Your data never leaves your computer.

Email me the link

DevTools runs on macOS, Windows and Linux. Open the link on your computer to install it.

Download DevTools Explore the tools

Free and open source for macOS, Windows and Linux.

Workspace

JWT Decoder

JSON Viewer

Your workspace

Open a tool, or search with the command palette.

Find a tool...⌘K

Quick Access

JSON Viewer

Code Playground

Regex Tester

JSON to Code

Hash Generator

UUID Generator

JWT Decoder

Token Decoded locally as you type

HeaderPayloadSignature

HeaderHS256

PayloadExpires in 59 min

Secret••••••••••••Verify signatureSignature verified

FormatMinifyValidateSort keysIndent 2 spacesSideBelow

JSON Input Paste

Output Copy

Waiting to formatUTF-8Local processing

Search tools...

Use arrows to navigateEnter to open · Esc to close

Features

01Tabs

One window. Many tabs.

Keep JSON Viewer, JWT Decoder and Hash Generator open in tabs. Each tab keeps its input, so you can come back to it later.

02Editor toolbar

Side by side, or stacked.

Put the output next to the input or below it. Format, minify, validate and sort keys with one click.

03Status bar

Processed on this machine.

The status bar shows it: Local processing. Every tool works without a network connection, and the app does not collect data about you.

04Command palette

⌘K to anything.

The command palette searches tool names and keywords. Arrow keys move, Enter opens, Escape closes.

AI tools

Clean it before the chatbot sees it.

5 tools for the AI part of your day. Strip secrets from a log, count tokens against a context window, and remove hidden data from images, videos and text. All of it happens before anything leaves your computer.

Secret & PII RedactorAI Tools

Text to shareAPI keyEmailPasswordIP

AI chatMasked values stay on this computer

Why did the deploy fail? [API_KEY_1] was rejected for [EMAIL_1].

Rotate [API_KEY_1] and ask [EMAIL_1] to confirm.

Restored: rotate and ask maria.lopez@acme.dev to confirm.

Mask it, send it, restore it.

API keys, tokens, passwords, emails and other personal data become placeholders. Paste the AI reply back and DevTools puts the real values in again.

Image Metadata CleanerAI Tools

IMG_2041.jpgExample metadata

Hidden in the originalClean copy

GPS location: Removed
Camera & EXIF: Removed
AI prompts: Removed
Content Credentials (C2PA): Removed

Same pixels. Less hidden data.JPEG, PNG and WebP · processed on your device

Share the image. Keep your privacy.

Strip location, camera details, AI prompts and Content Credentials before you share. The original pixels stay intact.

Video Metadata Cleaner

Remove AI labels (C2PA and XMP), GPS, camera details and timed metadata from MP4, MOV, M4V, 3GP, MKV and WebM videos. Keep the picture and sound without re-encoding. Review any metadata left in the clean copy.

Token Counter

Exact GPT token counts, estimates for Claude, Gemini and Llama, and a cost estimate from your own price table. Check your context window before you send.

AI Text Cleaner

Remove hidden characters, citation markers and Markdown from AI-written text. Straighten quotes and dashes.

The toolbox

58 tools. One sidebar.

The small jobs you usually open a random website for. Hover overTap a tool to see what goes in and what comes out.

/

Development Tools

Generators

Converters

Network

Time & Date

Media

Text Tools

Utilities

AI Tools

No tool matches that. Try a format name such as yaml, csv or base64.

Workflow

Built to stay out of the way.

⌘K

Command palette

Search every tool by name or keyword, such as sha, epoch or diff.

HashJSON ViewerJWT

Tabs and favorites

Keep several tools open at once. Right-click a tab to close others or tabs to its right. Star your daily tools.

devtoolsapp://open/json-viewer

Deep links

Open a tool from a script, a note or a launcher with one URL.

Light and dark

Follows your system theme, with native glass on macOS.

Privacy

Paste secrets here.
Not into a website.

Online formatters see every token, key and customer record you paste. DevTools works completely offline. Your data never leaves your computer.

Works completely offline. Disconnect Wi-Fi and every tool still runs.

No accounts, no analytics. The app does not collect data about you.

Open source. Read the code on GitHub and build it yourself.

ElementsConsoleNetworkSources

FilterPreserve log

NameStatusTypeSizeTime

0requests while tools run

0 requests0 B transferred0 local operations

What's new

Shipped in the latest release.

These notes come from the release-notes folder in the repository, so they match what you download.

Latest release note

DevTools v2.7.0

Open on GitHub

Highlights

Two new tools: Mermaid Renderer and Time Zone Converter.
Code Playground now runs JavaScript in a sandbox. Your code cannot reach the app or the network, and an endless loop no longer freezes the app.
The gradient builder is interactive. Drag stops on the preview bar, and move them with the keyboard.
Color Palette lets you edit the RGB and HSL channels and alpha directly.

New Tools

Mermaid Renderer shows a Mermaid diagram as you type. Start from a flowchart, sequence, class, ER, state, Gantt, mind map, pie, or Git graph template. Copy the SVG, or save it as SVG or PNG.
Time Zone Converter converts a date and time from one time zone to UTC, local time, and the zones you add. It handles daylight saving time changes and shows when the date changes.

Tool Improvements

Code Playground stops a run after 5 seconds or when you start a new run. Logs from async code now show in the console, and top-level await works.
Click the gradient preview bar to add a stop, up to 16 stops. The handles at 0% and 100% are no longer cut in half.
Press Enter in the color field to apply the color.
The color compare list checks up to 32 colors and tells you which entries it ignored.
The color blindness sample text now previews your working color. The severity slider goes down to 0%.
The color blindness image simulation limits the image size. If it rejects an image, it keeps the current image.

Show 1 more section

Support DevTools

DevTools is free and open source. If it saves you time, you can buy me a coffee or support it on Patreon.

Browse all notes

Download