Category: Code

Free code tools for developers — no signup, no install

Every tool here solves a specific formatting, decoding, or validation problem that developers hit daily. JSON that won’t parse because of invisible escaping. A JWT you need to inspect without pasting it into someone else’s server. An SVG that weighs 400 KB because Figma left every editor attribute in the file. A Markdown front-matter block that silently breaks your static site build.

These are not Swiss-army dashboards with thirty tabs. Each one does one job, does it in your browser, and gets out of the way. Nothing is uploaded, nothing requires an account, and nothing stops working after three uses.

What you can do right now

JSON Minifier — paste JSON, get the smallest valid version back. Beautify it the other direction. See the real compressed size (gzip and brotli), and catch duplicate keys your parser silently drops before they break production.

JSON Stringify and Unstringify — escape a JSON object into a string literal for embedding in code, or peel every layer of escaping off a log payload. Handles double-escaped and triple-escaped strings that copy-paste from Datadog, Kibana, and CloudWatch dumps.

JWT Decoder — paste a token, see the header and payload with every registered claim explained in plain language. The expiry counts down live so you know whether the token is still valid while you are debugging, not after you have already shipped the fix.

URL Encoder Decoder — encode or decode URLs and query parameters in Component, Full URL, or Form mode. Handles batch input, decodes recursively when a value has been encoded more than once, and breaks a URL into its individual parameters so you can see what each one carries.

Extract URLs from Text — paste an email thread, a log dump, a block of HTML, or any messy text and pull out every URL, domain, or email address. Deduplicate, sort, copy the list, or download it. Nothing leaves your browser.

SVG Minifier — drop an SVG file and strip the editor bloat that tools like Figma, Illustrator, and Inkscape leave behind. Removes unused attributes, optimises path data, cleans colours and numbers, and keeps the image scalable. See the before-and-after size so you know what you saved.

Markdown Front-Matter Validator — paste your front matter and instantly validate YAML, TOML, or JSON syntax. Auto-fixes the common mistakes (wrong indentation, unquoted dates, trailing commas), checks required fields per generator (Hugo, Astro, Jekyll, Next.js), and exports a JSON Schema you can commit to the repo so the whole team stays consistent.

Why these exist

Most of these jobs have an answer on the first page of Google already. The problem is what that answer does with your data. JWT decoders that send your token to a server. JSON formatters that cap paste length at 10 KB unless you pay. SVG optimisers that require a desktop install for batch mode.

Every tool here runs entirely in your browser. The code loads once, the data stays on your machine, and the result is yours to copy or download. No upload, no queue, no daily limit.

Articles on the formats behind the tools

The guides below go deeper into the formats these tools handle — how JSON escaping actually works under the hood, why SVG files balloon in size, what each JWT claim means and when to use it, and the mistakes that silently break builds. Written from the same debugging notes that became the tool specifications.