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DevToolKit is a collection of 19 free online developer tools that run entirely in the browser. No backend, no signup, no data ever leaves your machine. Built with Next.js 14 and Tailwind CSS. Tools include: JSON Formatter & Validator, JSON Tree Viewer with node path copying, YAML-JSON Converter, SQL Formatter, Base64 Encoder/Decoder (text + file drag & drop), URL Encoder, JWT Decoder, Hash Generator (SHA-1/256/384/512 via Web Crypto API), Password Generator, Cron Expression Parser with next run time calculation, PostgreSQL Config Generator (free PGTune alternative), UUID v4 Generator, QR Code Generator (PNG + SVG), Lorem Ipsum Generator, Regex Tester, Text Diff Checker, Unix Timestamp Converter, Color Converter (HEX/RGB/HSL), and HTTP Status Codes Reference. Every tool processes data locally using native browser APIs. No server-side processing, no cookies, no analytics tracking of input data.
Leo Editor
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DevToolKit.site's answer:
DevToolKit runs 100% in the browser with zero signup. Unlike CyberChef, which has a steep learning curve with its recipe-based interface, DevToolKit gives you 19 standalone tools โ each with a clean, focused UI for a single task. Unlike DevToys, it works on any device with a browser โ no desktop app installation needed. And unlike SmallDevTools or similar online toolkits, DevToolKit includes unique tools like a PostgreSQL Config Generator (a free PGTune alternative), a Cron Expression Parser that calculates next 10 actual run times, and a JSON Tree Viewer with click-to-copy node paths. Every tool uses native browser APIs like Web Crypto for hashing โ no data is ever sent to a server, which matters if you're working with production JWTs, API keys, or database configs.
DevToolKit.site's answer:
Backend and full-stack developers who deal with JSON, JWTs, SQL, cron jobs, and PostgreSQL configuration on a daily basis. DevOps engineers who need quick encoding, hashing, or regex testing without installing CLI tools. Developers who care about data privacy and don't want to paste production tokens or API responses into random websites that may log input data.
DevToolKit.site's answer:
I'm a backend developer with 10+ years of experience in Python and Go, working on distributed systems and microservices. Every day I was jumping between 5-6 different sites to format JSON, decode a JWT, test a regex, or convert a timestamp โ each one bloated with ads, cookie banners, and signup walls. One evening I decided to build all the tools I actually use into a single place where everything runs client-side. The first version had 15 tools and took a weekend to build with Next.js and Tailwind CSS. After getting feedback, I added a PostgreSQL Config Generator (because PGTune hasn't been updated in years), a JSON Tree Viewer, and an HTTP Status Code Reference. It's now at 19 tools and growing based on what developers ask for.
DevToolKit.site's answer:
Next.js 14 with App Router for server-side rendering and per-page SEO metadata. Tailwind CSS for styling with a custom dark theme. Web Crypto API (crypto.subtle) for SHA-1/256/384/512 hashing and cryptographically secure password generation โ zero external crypto libraries. FileReader API for client-side Base64 file encoding. All tools are React components with no backend โ the entire app is static and deployed on Vercel. Each tool is a separate route with its own metadata, canonical URL, and sitemap entry for independent Google indexing.
DevToolKit.site's answer:
DevToolKit is a free tool with no accounts, so we don't track individual users. It's used by individual developers and small teams who need quick, private access to common dev utilities without enterprise overhead. The tool is designed for anyone who works with APIs, databases, or web development and wants a fast, ad-free, privacy-respecting alternative to existing online tools.
DevToolKit.site's answer:
Three things set DevToolKit apart. First, it includes tools you won't find in other online toolkits โ a PostgreSQL Config Generator that replaces PGTune with hardware-aware tuning calculations, a Cron Expression Parser that doesn't just describe the schedule but calculates the next 10 actual execution timestamps, and a JSON Tree Viewer where you click any node to copy its full JavaScript path like data.users[0].email. Second, every tool uses native browser APIs instead of external libraries โ hashing runs through Web Crypto API with hardware acceleration, passwords use crypto.getRandomValues(), file encoding uses FileReader โ meaning zero dependencies and zero data transmission. Third, each of the 19 tools lives on its own URL with dedicated SEO metadata, so you can bookmark devtoolkit.site/jwt-decoder/ and go straight to it โ no navigating through menus or loading tools you don't need.
Based on our record, Leo Editor seems to be more popular. It has been mentiond 13 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
What are your experiences with literate programming for handover of code? I am thinking of tools like noweb (https://en.wikipedia.org/wiki/Noweb), LEO (http://leoeditor.com/) org-mode (http://cachestocaches.com/2018/6/org-literate-programming/), scribble/lp2 (https://docs.racket-lang.org/scribble/lp.html#%28part._scribble_lp2_.Language%29), My experience so far is that it can be a fantastic tool for documenting... - Source: Hacker News / over 3 years ago
I know what folding is, that's just not what I want. I want to completely hide everything that is not related to the current function. For a while, I used http://leoeditor.com/ where I could have every function/method as a node in a tree, with the node body containing just that. Looking for a way to achieve the same in vim if possible. Source: almost 4 years ago
The lack of good node/graph based APIs for Org Mode is my beef as well. When you compare it with the APIs of the Leo Editor[1], Org pales in comparison. Manipulation that is trivial in the Leo Editor can be quite a pain in Org mode. [1] https://leoeditor.com/. - Source: Hacker News / about 4 years ago
> What outliners do you know which allow end-users to feed their data into formulas for processing it without using general-purpose programming languages? Bit of a pointless constraint, the talk is about outliners, not no-code-datamangment. Which tool today does this even offer on a useful level? But you can look at leo editor (https://leoeditor.com), which is active for 20+ years, fully scriptable and extendable.... - Source: Hacker News / about 4 years ago
Leo is a pretty amazing project: Edward K. Ream treats it as his life's work, it seems to me, and his energy on the mailing lists, constantly thinking in public, is an inspiration. https://leoeditor.com/. - Source: Hacker News / about 4 years ago
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