Sometimes you want a rough sense of how much of a script is whitespace, or you need to inline a small snippet into a page without spinning up a build.
- Free
- No signup
- Fast
- Privacy-friendly
Back to Category
Developer tools
JS Minifier
Code
Free · API · MCPToolYour platform
Use JS Minifier three ways
The free JS Minifier on this page works in your browser. The same workflow is available via REST API for apps and via MCP for Cursor, Claude, and other agents — one API key, one plan, one quota. This tool is part of the developer-apis module under Developer Tools.
- Free in browserUse JS Minifier here — no account required.
- REST APICall from your server with
X-Api-Key. - MCP for agentsConnect Cursor or Claude to ToolYour MCP with the same key.
- 1. Get an API keySign in and open Dashboard → API Keys (works for REST and MCP).
- 2. Call or connectUse the REST API from your server, or paste the MCP URL into your agent config.
- 3. Same qualityOutput matches the free web tool across all three surfaces.
What is JS Minifier?
Sometimes you want a rough sense of how much of a script is whitespace, or you need to inline a small snippet into a page without spinning up a build. This JS minifier strips block and line comments, collapses runs of whitespace, and tightens spacing around braces, brackets, parentheses, commas, semicolons, and equals signs, returning the result with original and minified byte counts.
The warning is returned with every response and deserves attention: this is a lightweight textual pass, not Terser or esbuild. It does not parse the code, which means it cannot rename identifiers, eliminate dead code, or reason about scope — and it also means constructs where line breaks are semantically significant, such as automatic semicolon insertion or template literals spanning lines, can be affected. Always run the output before shipping it. For production bundles, use your build toolchain. To make a minified file readable again, JS Formatter expands it.
Browser use is free and needs no signup. The same job runs over REST at POST https://api.toolyour.com/api/v1/developer-apis/js-minifier and over MCP at https://api.toolyour.com/mcp — one API key, one shared monthly credit pool, 1 credit per successful call.
What are common questions about JS Minifier?
Is this safe for production bundles?
Use esbuild, Terser, or your bundler for production. This is a lite helper for snippets and quick size comparisons, and the response says so.
Does it rename variables?
No. Identifier mangling requires parsing and scope analysis. This pass only removes comments and unnecessary whitespace.
Can minifying here break my code?
It can, where line breaks carry meaning — automatic semicolon insertion and multi-line template literals in particular. Smoke-test the output every time.
Does it handle TypeScript?
No. Transpile to JavaScript first; type annotations are not valid input for this pass.
What are the key features of JS Minifier?
Comment and whitespace stripping
Block and line comments plus redundant spacing removed in one pass.
Byte counts returned
Original and minified sizes make the comparison concrete.
Warning travels with the result
Every response repeats the not-Terser caveat so it reaches scripts and agents too.
How do you use JS Minifier?
Paste the JavaScript
A snippet or small file rather than an entire application bundle.
Compare the sizes
See how much of the file was comments and whitespace.
Run the output
Execute the minified version and confirm behaviour is unchanged before using it.
Lite pass versus a real minifier
The gap is large and worth understanding. A lite pass, like this one, works on text: comments go, whitespace collapses, and the result is usually a modest percentage smaller. A real minifier such as Terser or esbuild parses the source into a syntax tree and can then rename local identifiers to single characters, remove code that can never execute, inline constants, and simplify expressions — typically a far larger reduction, with a source map so stack traces stay useful.
Text-based passes also carry a risk a parser-based tool does not: without understanding the grammar, removing a newline can change meaning. That is the entire reason the warning is attached to every response rather than buried in documentation.
When a quick pass is the right tool
Three cases justify it. Estimating — you want to know how much of a file is comments before deciding whether minification is worth wiring up. Inlining — a few lines going into a page head where a build step would be overkill. Comparing — checking a vendor snippet's minified size against the version you were given.
Anything shipping to users at scale belongs in a build pipeline. For the stylesheet half of the same page, CSS Minifier does the equivalent job, and HTTP Headers Checker will tell you whether the asset is being served compressed, which usually matters more than the minification itself.
Which formatter and utility tools sit in this cluster?
Where do you browse more developer tools tools?
- Developer Tools tools
Browse the full Developer Tools category on ToolYour.
- Marketing Tools tools
Build UTM links, check ads copy limits, QA email subjects, and calculate ROAS/CPC/CTR — free in the browser; R
- Security Tools tools
Check HTTP security headers, TLS, cookies, JWTs, passwords, hashes, and SPF/DKIM/DMARC — free in the browser;
Related tools
developer tools
Color Converter
Convert a hex, rgb(a), or hsl(a) colour into all four notations at once, preserving alpha.
Freedeveloper tools
CSS Minifier
Strip comments and whitespace from CSS and report original versus minified byte counts.
Freedeveloper tools
Cron Expression Parser
Parse a cron expression and list the next eight UTC run times so you can sanity-check a schedule.
Freedeveloper tools
Cron Expression Generator
Build a five-field cron expression from schedule fields and preview the next five run times in UTC.
Freedeveloper tools
Regex Generator
Return a vetted regex preset for email, URL, IPv4, UUID, digit, or slug shapes, each with a stated limitation.
Freedeveloper tools
SQL Validator
Flag empty statements, unbalanced parentheses, stacked statements, and missing SQL verbs without a database.
Freedeveloper tools
SQL Formatter
Reformat SQL with keyword casing and clause line breaks so long queries become reviewable.
Freedeveloper tools
JS Formatter
Pretty-print JavaScript with Prettier and the babel parser, surfacing syntax errors instead of hiding them.
Freedeveloper tools
CSS Formatter
Pretty-print CSS with Prettier for readable stylesheets, cleaner diffs, and easier specificity review.
Freedeveloper tools
HTML Formatter
Pretty-print HTML with Prettier so templates and response bodies become readable and reviewable.
Freedeveloper tools
IP Address Tools
Validate and classify IPv4 or IPv6 strings, including private and loopback ranges, with no external lookup.
Freedeveloper tools
User Agent Parser
Parse a User-Agent string into browser, operating system, and device hints for log triage.
Free
Popular in Developer Tools
developer tools
Color Converter
Convert a hex, rgb(a), or hsl(a) colour into all four notations at once, preserving alpha.
Freedeveloper tools
CSS Minifier
Strip comments and whitespace from CSS and report original versus minified byte counts.
Freedeveloper tools
Cron Expression Parser
Parse a cron expression and list the next eight UTC run times so you can sanity-check a schedule.
Freedeveloper tools
Cron Expression Generator
Build a five-field cron expression from schedule fields and preview the next five run times in UTC.
Freedeveloper tools
Regex Generator
Return a vetted regex preset for email, URL, IPv4, UUID, digit, or slug shapes, each with a stated limitation.
Freedeveloper tools
SQL Validator
Flag empty statements, unbalanced parentheses, stacked statements, and missing SQL verbs without a database.
Freedeveloper tools
SQL Formatter
Reformat SQL with keyword casing and clause line breaks so long queries become reviewable.
Free