Minifier Suite
Local processing guarantee: Code is minified purely inside your browser. No files are uploaded to servers.
Input Source Code
Minified Output
The Importance of Code Minification
Minification is the process of removing all unnecessary characters from source code without changing its functionality. This includes stripping comments, collapsing whitespace, shortening variable names (in compiler-based pipelines), and removing redundant semicolons or block syntax. Reducing file sizes directly translates to faster page loads, decreased network bandwidth usage, and improved Web Vitals.
JavaScript Minification
JavaScript is compressed with Terser, a real AST-based minifier: it parses your code to a syntax tree, so strings, template literals, and regular expressions are never corrupted and automatic-semicolon-insertion hazards are handled correctly — guarantees a regex pass cannot make. CSS uses csso, and HTML uses a structure-aware pass that never touches the contents of <pre>, <script>, or <style>.
CSS Minification
Minifying CSS involves removing comment block structures, collapsing extra layout spacing, and stripping spaces around curly braces ({, }), colons (:), and semicolons (;). The trailing semicolon in any property block is also safely removed as permitted by the CSS standard.
HTML Minification
HTML minification strips out all developer comments (<!-- -->) and collapses multi-line text indentations to single spaces. Spacing between closing and opening angle brackets of adjacent elements (> <) is completely eliminated to make layouts highly compact.
Built and maintained by Meet Shah · Last updated
What this tool is used for
- Checking how much a snippet shrinks before adding a build step to do it properly.
- Producing a compact one-liner to paste into a constrained field or an inline attribute.
- Comparing the size of two implementations fairly, with whitespace removed from both.
- Stripping comments from a file before sharing it, when the comments are internal.
- Estimating transfer savings for a page you cannot rebuild.
Frequently Asked Questions
- What does minification do?
- Minification removes whitespace, comments, and redundant characters from HTML, CSS, or JavaScript — shrinking file size without changing functionality. Smaller files mean faster page loads for users.
- Will minified code break in production?
- Not if the original is valid. Minifiers preserve all logic; they only strip characters that don't affect execution. Always test minified output in your target browsers before deploying.
- How much size reduction should I expect?
- Typically 20–40% for HTML/CSS and 30–60% for JavaScript. Scripts with many comments or verbose names see the highest gains. Gzip or Brotli on top of minification reduces sizes even further.
- Can I undo minification?
- Not with this tool — original whitespace and names are gone once minified. Always keep your unminified source in version control. Use a formatter to make minified code readable (variable names won't be restored).
- What's the difference between minification and gzip compression?
- Minification removes characters from the source text. Gzip/Brotli encodes the binary at the network layer. They're complementary — minify first, then serve with gzip for the maximum file-size reduction.
Common errors and gotchas
- Minifying JavaScript that relies on automatic semicolon insertion, where removing a line break changes behaviour.
- Stripping comments that were load-bearing, such as a licence header or a build directive.
- Removing whitespace between inline HTML elements, which changes rendering.
- Expecting the savings a real build tool achieves. Whitespace removal is a fraction of what renaming and tree-shaking do.
- Minifying a file that is already served with gzip and assuming the savings add up linearly. They do not.