About Deflate Decompress
Deflate Decompress takes Base64-encoded deflate data and turns it back into readable text. The sample that loads with the page is a complete working example: a short string, compressed and encoded, ready to be restored in one keystroke. The result recalculates live as the input changes, so there is no button to press and no intermediate step to wait for.
Under the hood the page uses the browser's own decompression stream, which means the work happens locally and the data never leaves the machine. The accepted form is the deflate variant that carries the zlib container - the same form the Deflate Compress tool on this site produces, which makes the two pages a matched pair for round-tripping text through a compressed representation.
The boundaries are worth knowing before you rely on it. Gzip data, which carries a different header, belongs to the Gzip Decompress page; a raw deflate stream without the zlib wrapper will not decode here; and a stream that decompresses to binary rather than text comes back mangled, because the output is forced through a UTF-8 reading. Invalid input yields an error in place of a result rather than a partial answer.
How to use Deflate Decompress
- 1 Paste the Base64-encoded deflate data into the panel, or start from the loaded sample.
- 2 Read the restored text, which appears live without a button press.
- 3 Check the error message if nothing appears - it means the input was not valid Base64 or not a zlib-wrapped deflate stream.
- 4 Use the Deflate Compress tool to turn text back into this form when you need the round trip.
Frequently asked questions
Why does my gzip data fail here?
Gzip carries its own header around the deflate stream, which this page does not expect. Take gzip-encoded data to the Gzip Decompress tool, and keep this page for the zlib-wrapped form that the Deflate Compress tool produces.
What happens if the stream contains binary rather than text?
The output is read as UTF-8 text, so bytes that do not form valid text come back as replacement characters. The page is for streams that decompress to text; binary payloads are not recoverable from the result.
Can it decompress a raw deflate stream without the zlib wrapper?
No. The page accepts the zlib container form, which is what the deflate label of the browser decompression stream expects. A headerless raw stream fails, and there is no setting to switch container modes.
Is there a size limit on the input?
There is no fixed limit beyond what the browser can hold in a text panel, but the whole stream is decompressed in one pass with no progress indicator. Very long inputs work but are not fast, and there is no way to save the result other than copying it.
Free, online, and private
Free to use
Deflate Decompress is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Deflate Decompress behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Input | one text panel holding Base64-encoded deflate data; the sample is eJzzSM3JyVcozy9KVQgBAP//AwA= |
| Stream format | the deflate variant that carries the zlib container, created through the browser DecompressionStream with the deflate label |
| Pipeline | Base64 is decoded to bytes, piped through the decompression stream, and the result is read back as UTF-8 text |
| Live behaviour | the output is recalculated as the input changes, with no separate button press |
| Counterpart | the Deflate Compress tool on the same site produces exactly the form this page consumes |
| Failure mode | input that is not valid Base64 or not a valid deflate stream yields an error in place of a result |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Deflate Decompress does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- Only the zlib-wrapped variant is accepted. A raw deflate stream without the two-byte header fails, and gzip data - which carries its own different header - has to be taken to the Gzip Decompress page instead of this one.
- The output is plain text. A deflate stream that decompresses to binary bytes is forced through a UTF-8 decoder, so anything that is not real text comes out as replacement characters rather than as recoverable bytes.
- There is no file upload and no size control. Input arrives by pasting only, and a very long stream is decompressed in one pass with no progress indicator and no way to save the result other than copying it out of the panel.
Tested and documented by itoolnet, the team that builds and maintains this site.