SVG's scalability and CSS flexibility don't help when platforms like OGP, email, and Slack simply reject it. Here's why PNG is still necessary and how the Canvas API handles the conversion.
Free Developer Tools, Right in Your Browser
$ devtools --philosophy
Free developer tools, ready in your browser
From API key generation to an SVG viewer, ULID generation, and color palettes: a free toolbox for everyday development work. Wondering about the edge cases? Several tools come with an article that walks through how they actually behave.
Take a look at the dashboard$ ls tools/ --by-category
Browse all 12 tools
Formatter
- JSON FormatterPaste minified or single-line JSON to instantly validate, pretty-print, or compress it — handles deeply nested objects, arrays, and escaped strings entirely in your browser, no upload required.
- SQL FormatterClean up cramped, single-line, or ORM-generated SQL into properly indented queries — handy before a code review, when sharing a query in a PR, or pasting into documentation.
Generator
- UUID GeneratorGenerate RFC 9562-compliant UUIDs in bulk — random v4, time-ordered v7 for sortable primary keys, or legacy v1 — ready to copy straight into seed data or test fixtures.
- ULID GeneratorGenerate ULIDs in bulk — a UUID alternative with a built-in millisecond timestamp, so records sort chronologically by ID alone. Useful for primary keys, event logs, or anywhere insertion order matters.
- Password GeneratorGenerate strong random passwords with custom length and character sets — useful for one-off secrets like a new account sign-up or a server config, when you need a password now rather than reaching for a password manager.
- API Key GeneratorGenerate random API keys and secret tokens for local development, MCP servers, or test fixtures — pick the length and character set, then drop the result straight into a `.env` file or mock config.
Converter
- URL EncoderPercent-encode or decode URLs, query parameters, and special characters — handy for debugging broken links, building query strings by hand, or inspecting an encoded parameter you received from an API.
- UNIX Timestamp ConverterConvert between Unix epoch time (seconds or milliseconds) and human-readable dates in any timezone — handy for decoding a timestamp buried in a log file or an API response without doing the math yourself.
Image & Design
- SVG ViewerPreview an SVG file and export it as a PNG — useful when a tool or platform doesn't accept vector graphics and you need a raster version of an icon or logo without opening a design app.
- Color PaletteCompare hex or RGB color codes side by side and generate a gradient between two colors — useful for exploring a palette or previewing a CSS gradient before writing the code.
HOW IT WORKS
What's Behind Each Tool
We dug into how each tool actually works, including the edge cases that trip people up, and wrote it all down. Every article links straight back to the tool it covers.
The same bytes encode differently in Base64 vs Base64URL in three distinct ways: character substitution, padding, and how = behaves in URLs. Most JWT decoding failures trace back to mixing these up.
Plain ULID generation breaks ordering within the same millisecond. We read the monotonicFactory source to see exactly how it increments the random bits, and compare that with UUID v7.
Splitting 192.168.1.0/24 across four departments with different host counts, this post traces why allocating from the smallest subnet first leaves the address space too fragmented for later, larger blocks.
Encoding a single query string value with encodeURI lets characters like & and = survive, which can break the structure of the URL itself. This article walks through an actual case where the URL breaks and clarifies the boundary between encodeURI and encodeURIComponent.
The "-2" in the standard CIDR host-count formula comes from reserving a network and broadcast address — and that's exactly why /31 and /32 don't follow it.
Using 192.168.1.130/26 — a CIDR that splits in the middle of an octet — as an example, we trace exactly how bitwise AND and OR produce the network and broadcast addresses.
Explains the relationship between UNIX time's fixed 86400-second day and leap seconds, and what to watch out for when converting.
Explains the internal structure of randomly generated v4 and chronologically sortable v7, and the use cases each is best suited for.
No install, no data leaves your browser
- Nothing you paste or type is ever sent to a server — every conversion and format runs locally in your browser.
- No sign-up, no app to install — open the page and the tool is ready.
- Every tool is a plain client-side implementation, so you can read exactly what it does — nothing runs server-side out of view.