Data
JSON and CSV tools for formatting, validation, preview, editing, and conversion across API debugging, data cleanup, table handling, and cross-system migration.
Explore categoryBrowse by use case
Pick the section that matches the task at hand. Patching a config? Start in Data. Debugging an API? Try Encode and Security. Cleaning up screenshots, scans or PDFs? Try File.
-
-
File
Tools for working with images and PDFs: image compression and format conversion, Base64 round-trip, metadata inspection and cleanup, PDF split, merge, organize, and watermark. Everything runs locally in your browser.
Explore category -
Encode
Encoding and scannable-code tools for Base64, Base64url, URL percent-encoding, HTML entities, query parameters, QR codes, and barcodes across API debugging, template content, and label workflows.
Explore category -
Text
Text utilities for counting, case conversion, find-and-replace, whitespace cleanup, and line-level processing across writing, development, logs, SEO copy, and bulk content work.
Explore category -
Time
Date and time tools for Unix timestamps, ISO/UTC parsing, timezone conversion, date differences, date arithmetic, business days, and world city clocks.
Explore category -
Security
Security utilities for JWT inspection, strong password generation, Hash digests, and HMAC signatures across authentication debugging, integrity checks, and API signing.
Explore category -
Network
Network and browser troubleshooting tools for User-Agent parsing, URL analysis, CIDR subnet calculation, and runtime browser capability checks.
Explore category -
Generator
Generators for UUIDs, custom IDs, random numbers, random strings, slugs, template codes, and structured JSON fake data for testing, demos, mock APIs, and seed data.
Explore category -
Design
Design and frontend utilities for color formats, CSS gradients, accessibility contrast, and OKLCH palette generation across design systems, theme work, and UI debugging.
Explore category -
Reference
Developer references for HTTP status codes and TCP/UDP port numbers across API debugging, website troubleshooting, firewall configuration, and security audits.
Explore category
A few we put real work into
These are not a thin wrapper over a library — each has details that mattered to us. If you only try one or two tools from this site, start with these.
- Data
JSON Formatter
Format, validate, fold sections, and jump to a path. Errors point to the exact line and column.
- Data
JSON Diff
Compares two JSON values side by side. Additions, removals and edits stay aligned even inside deeply nested structures.
- Text
Regex Tester
Live matching with capture-group highlighting, a reference of common patterns, and a replace preview so you can debug why something is not matching.
- File
Organize PDF
Drop multiple PDFs in, reorder pages across files, rotate or delete pages, and download a single PDF.
- File
PDF Watermark
Apply a text or image watermark with control over opacity, angle, tiling density and page range.
- Security
JWT Inspector
Expands Header and Payload, shows the algorithm, and verifies HMAC signatures locally.
- Time
Cron Expression Tool
Translates the expression into plain English and lists the next several run times so you can double-check it.
- Encode
QR Code Generator
Generates QR codes with adjustable error correction, size and embedded logo. Supports URL, Wi-Fi, vCard and other content types.
- Encode
Morse Code Converter
Converts text to Morse and back, with audio playback and a visual rhythm display.
What this site is trying to do
These small tasks are spread across dozens of sites, and the search results are usually buried in ads. DevKitLab tries to do a few things well: gather these tasks in one place, build each tool so it actually solves the problem, and keep the input, output, copy and download patterns consistent between tools.
-
You should not have to search every time
Formatting JSON, decoding a JWT, splitting a PDF, looking up an HTTP code — these come up several times a day. Opening a different ad-heavy page for each one is not fun. Bookmark DevKitLab and enter through a category or the tool list.
-
The tools are not there to pad the list
A handful of tools got real attention. JSON Diff stays accurate inside deeply nested structures. Regex Tester highlights capture groups and explains each segment. PDF Organize lets you drop multiple PDFs in and reorder pages across files. Cron Expression translates the expression into plain English and lists the next several run times. Detail is the difference between a tool that looks fine and one that helps.
-
Local by default
JSON formatting, Base64 encoding, timestamp conversion, text cleanup, PDF split and merge, image compression all run in your browser. Nothing gets sent to a server, so you can use them on temporary API responses, JSON with credentials, or PDFs you would rather not upload. The few tools that do need network access say so on the page.
-
Notes that actually explain things
The timestamp tool spells out the difference between seconds and milliseconds. Base64 separates plain text, URL-safe, and file modes. JWT shows the Header and Payload split and tells you which signature types can be verified locally. Error messages try to be specific — "missing comma at line 7" rather than "invalid JSON".
Questions we hear often
A few questions about pricing, how data is handled, and what the tools can or cannot do.
-
Do I need to pay or sign in?
Neither. Every tool opens directly. There is no account system and no per-action limit.
-
Will my data be uploaded?
For most tools, no. JSON, Base64, timestamps, text utilities, PDF split and merge, image compression — these run in your browser. The few tools that do depend on a network call (like some barcode scans) say so on the page.
-
How many tools are there?
About 66 at the moment, grouped under ten categories: Text, Data, Encode, Security, Network, File, Design, Time, Generator, and Reference. The full list lives under "Browse by use case".
-
What makes this different from other utility sites?
A handful of tools (JSON Diff, Regex Tester, PDF Organize, Cron Expression, and others) got real attention rather than being thin wrappers. The input, output, copy and download patterns are kept consistent across tools so you do not relearn each one. And there are no popup ads.
-
Why does this tool give a different result than another site?
The same operation can mean slightly different things. Timestamps could be seconds or milliseconds. Base64 has standard and URL-safe variants. Cron has the seven-field standard and Quartz extensions. When results differ, check the notes on the tool page.
-
Can I copy or download results?
Yes. Text results have a one-click copy. Generated images, PDFs and files download directly.
-
Does it work on mobile?
Yes — the layout adapts. Tools that depend on dragging large files (like PDF Organize) work best on a desktop.
-
Will this keep being updated?
Yes. New tools and improvements keep landing, and existing ones get adjusted based on feedback. If something feels off, the Contact page is open.