About DevMicroTools
A small collection of developer utilities that run entirely in your browser.
What this is
Most developers keep a handful of browser tabs open for the same small jobs — formatting a JSON response, decoding a token, comparing two config files, checking what a timestamp means. This site is those jobs, collected in one place, built to be fast and to stay out of the way.
Everything runs in your browser
There is no backend. No server processes your input, because there is no server beyond the one that sent you this page. Every tool is JavaScript executing in your own tab, using the browser's built-in APIs — the Web Crypto API for hashing, signature verification and AES/RSA encryption, the native regular expression engine for pattern testing,Intl for date formatting.
This matters practically, not just philosophically. It means you can paste a production JWT, an API response containing customer data, or an internal config file without that data leaving your machine. You do not have to take this on trust: open your browser's developer tools, switch to the Network tab, and use any tool on the site. You will see no outbound requests carrying your input.
How it is built
The site is static HTML generated by Astro. Each tool page ships one small interactive component and nothing else — no framework runtime on pages that do not need one, no analytics that follow you around, no cookie banner standing between you and a text box.
Privacy and funding
The site uses privacy-friendly, cookieless analytics that record page views and performance timings — not who you are or what you typed. It is funded by display advertising, kept to a small number of clearly-marked slots that never sit between you and a tool's controls. See the privacy policy for the specifics.
Corrections and requests
If a tool gives a wrong answer, that is a bug worth fixing — these are small, well-tested functions and they should be correct. If there is a utility you keep wishing were here, that is worth knowing too. New tools are added regularly.
Open source components
Almost everything here uses native browser APIs. Twenty-four third-party libraries are included for the specific jobs the browser has no built-in for — every tool's own page also links the library it uses. All twenty-four licences permit commercial use.
| Library | Licence | Used in |
|---|---|---|
diff | BSD-3-Clause | Diff Checker |
blueimp-md5 | MIT | Hash Generator (text MD5, since the Web Crypto API deliberately omits it) |
spark-md5 | MIT | Hash Generator (file MD5) |
qrcode-generator | MIT | QR Code Generator |
js-yaml | MIT | JSON, YAML, CSV & XML Converter (YAML) |
sql-formatter | MIT | SQL Formatter |
terser | BSD-2-Clause | HTML / CSS / JS Minifier (JavaScript) |
bcryptjs | BSD-3-Clause | Bcrypt Generator/Checker |
svgo | MIT | SVG Optimizer |
@jsquash/oxipng | Apache-2.0 | Image Compressor (extra lossless PNG pass) |
fflate | MIT | Image Compressor (zip download of a batch), PDF Compressor (stream compression) |
image-q | MIT | Image Compressor, Image Cropper, Image Format Converter (lossy PNG mode) |
pdf-lib | MIT | PDF Compressor (reading and rewriting PDFs) |
compromise | MIT | Case Converter, Word Counter (Sentence case proper-noun dictionary lookup, loaded only on click) |
gpt-tokenizer | MIT | LLM Token Counter (OpenAI's published token vocabularies) |
marked | MIT | Markdown Previewer (Markdown → HTML) |
DOMPurify | MPL-2.0 or Apache-2.0 | Markdown Previewer (sanitizes the rendered HTML) |
turndown | MIT | Markdown Previewer (HTML → Markdown) |
turndown-plugin-gfm | MIT | Markdown Previewer (GFM tables, strikethrough, task lists) |
onnxruntime-web | MIT | Background Remover, Face & Plate Blur (on-device AI models via WebAssembly) |
@huggingface/transformers | Apache-2.0 | Case Converter, Word Counter (Sentence case AI model, via WebAssembly, loaded only on click) |
mermaid | MIT | Mermaid Diagram Generator |
@noble/ciphers | MIT | AES Encrypt / Decrypt (optional Pure JS engine, loaded only when chosen) |
@noble/hashes | MIT | AES Encrypt / Decrypt (PBKDF2 for the Pure JS engine) |
AI models
Three tools also download a pre-trained model file — not an npm package like the libraries above, but a set of weights a neural network was trained on — to run entirely on-device via WebAssembly (onnxruntime-web or@huggingface/transformers, both listed above). All are freely licensed for commercial use, and all run exactly like every other tool here: nothing leaves your browser, ever, for the model to process.
| Model | Licence | Used in |
|---|---|---|
| u2netp | Apache-2.0 | Background Remover |
| Ultra-Light-Fast-Generic-Face-Detector-1MB | MIT | Face & Plate Blur |
| distilbert-NER | Apache-2.0 | Case Converter, Word Counter (Sentence case proper-noun detection) |
The site itself is open source (MIT licensed) — read the code powering any tool, or the privacy claims above, on GitHub.