Brotli Decompress

What this tool does

Brotli Decompress takes a Brotli-compressed payload — the codec behind HTTP content-encoding: br and most modern JavaScript/CSS asset bundles — and shows you the original data. Paste the blob as Base64 or hex, and the decompressed bytes appear as text, hex, or Base64. Decoding is pure Rust compiled to WebAssembly and runs entirely in the page, so a payload copied out of a production response or a customer bug report never leaves your machine.

Worked example

Paste this Base64 payload with Input encoding on Auto-detect and Show result as on Text:

GzYA6IzTFfMjhHUPwW2pr1bT4W8HRZOIyaLT1YpIQtBEajXzAUMiA3t2HQ3lRtbqeY1Rlg8=

You get the JSON that was compressed into it:

{"user":"ada","roles":["admin","deploy"],"active":true}

Turn on Show size and ratio stats and the result is prefixed with a summary before the payload:

Compressed:   53 bytes
Decompressed: 55 bytes
Ratio:        1.04x (decompressed / compressed)
Space saved:  3.6%

(Fifty-five bytes of JSON is far too small for Brotli to help — the preset chip High-ratio blob with stats shows the same summary on a payload that compresses 30× instead.)

Where Brotli payloads come from

• HTTP response bodies. Servers negotiate Accept-Encoding: br and return a Brotli-compressed body. Copying that body out of a proxy log or a curl --raw capture leaves you with bytes no editor can read.
• Asset bundles. Build pipelines ship pre-compressed .br files next to their .js/.css originals, and CDNs serve them directly.
• Embedded blobs. Config, telemetry, and cache entries are often Brotli'd and then Base64'd so they survive JSON or a URL.

Encodings

Input encoding is Auto-detect by default. Auto-detection here is verified, not guessed: a short Base64 string can consist entirely of hex characters, so the tool decodes the payload both ways and keeps whichever one actually Brotli-decompresses. Force Base64 or Hex when you already know the form and want a precise error instead of a fallback.

• Base64 accepts the standard and URL-safe alphabets, with or without = padding.
• Hex ignores an optional 0x prefix and is case-insensitive.
• Both ignore ASCII whitespace and line breaks, so a wrapped paste works unchanged.

Show result as defaults to Text (UTF-8). Switch to Hex or Base64 when the payload decompresses to binary — a font, an image, a protobuf — instead of readable text.

Limits and edge cases

• 8 MiB of compressed input and 16 MiB of decompressed output. The payload is held in WebAssembly memory, so an unbounded blob would exhaust the tab; past these caps you get a clear error rather than a crash. Large .br files are better handled as a file download by the file-compressor tool (operation=decompress, format=brotli).
• Brotli has no magic number. Nothing about the first few bytes proves a blob is Brotli, which is why this tool never rejects input up front. If the decode fails and the bytes carry a different codec's signature, the error names that codec and the tool that handles it — gzip → gunzip, zlib → raw-inflate, xz or raw LZMA → lzma-decompress, LZ4 → lz4-decompress, zstd → file-compressor, bzip2 or tar → archive-extractor, ZIP → unzip, 7-Zip → 7z-extract.
• A truncated payload cannot be recovered. Brotli decoding is sequential, so half a stream produces a decode error, not half the text. Copy the whole compressed body.
• An empty payload is valid. Brotli can encode zero bytes, and the result is an empty output rather than an error.
• Text output rejects non-UTF-8 bytes on purpose — mojibake hides real data, so the error tells you to switch to hex or Base64 instead.

FAQ