String Decompressor (GZIP/LZ)
Decompress GZIP+Base64, DEFLATE+Base64, and LZ-String compressed payloads back to readable text instantly in your browser. Supports all three LZ-String variants — Base64, UTF-16, and URI-safe. No server upload and no signup required.
Compression Algorithm
Supported Formats
GZIP+Base64 — used by server-side APIs, HTTP responses, and tools like the Text Compressor (GZIP). DEFLATE+Base64 — raw DEFLATE without GZIP framing. LZ-String — used by localStorage compression libraries, URL state encoding, and client-side caching tools.
Why Use Our String Decompressor?
Instant String Decompression
Decompress GZIP+Base64, DEFLATE+Base64, and LZ-String payloads instantly in your browser. The string decompressor processes everything locally — no upload wait, no server round-trips, results in milliseconds.
Secure String Decompressor Online
Your compressed payload never leaves your device. The string decompressor runs entirely in your browser — no server uploads, no data transmission, 100% private. Safe for API payloads, tokens, and sensitive data.
String Decompressor Online — No Installation
Use the string decompressor directly in any modern browser with no software downloads, no plugins, and no account required. Supports GZIP, DEFLATE, and all three LZ-String encoding variants.
100% Free Forever
The string decompressor is completely free with no signup, no premium tier, no payload size limits, and no ads. Decompress unlimited strings at zero cost, forever.
Common Use Cases for String Decompressor
API Response Debugging
Decompress GZIP+Base64 encoded API responses to inspect the raw JSON payload. The string decompressor lets you read compressed API data without writing any code or setting up a local environment.
Compressed Payload Inspection
Debug compressed payloads in network requests, log files, or message queues. Paste the Base64 string directly into the string decompressor to see the original content instantly.
localStorage Data Recovery
Recover and inspect data stored in localStorage using LZ-String compression. The string decompressor supports all three LZ-String encoding variants — Base64, UTF-16, and URI-safe.
URL State Decoding
Decode LZ-String URI-encoded state from URL query parameters used by client-side routing libraries. The string decompressor restores the original JSON or text state from compressed URL params.
Compressed Cookie Inspection
Inspect LZ-String compressed cookie values used by session management and state persistence libraries. The string decompressor decodes the compressed value back to readable JSON or text.
Compressed Token Analysis
Analyse GZIP+Base64 encoded tokens, configuration blobs, or serialised state objects. The string decompressor reveals the original content without requiring server-side tooling.
Understanding String Decompression
What is a String Decompressor?
A string decompressor reverses the compression process — it takes a compressed, encoded string and restores it to the original readable text. Compressed strings appear in many contexts: API responses encoded as GZIP+Base64, localStorage values compressed with LZ-String, URL query parameters encoded with LZ-String URI, and raw DEFLATE payloads. The string decompressor supports all of these formats and runs entirely in your browser using the native DecompressionStream API for GZIP/DEFLATE and a pure-JS LZ-String implementation for LZ variants.
How Our String Decompressor Works
- Select the Algorithm: Choose the compression format that matches your input — GZIP+Base64, DEFLATE+Base64, LZ-String Base64, LZ-String UTF-16, or LZ-String URI. If you are unsure, try GZIP+Base64 first as it is the most common format for API payloads.
- Paste Your Compressed String: Paste the compressed string into the input panel. The string decompressor accepts any length of input — from short localStorage values to large API response payloads.
- Decompress and Inspect:Click "Decompress String" and the decompressed text appears instantly in the output panel. Copy it to clipboard or download it as a .txt file. Your data never leaves your browser.
Supported Compression Formats
- GZIP + Base64:The most common format for compressed API payloads and HTTP responses. The string decompressor decodes the Base64 string and decompresses it using the browser's native
DecompressionStreamAPI with the 'gzip' format. - DEFLATE + Base64: Raw DEFLATE compressed data encoded as Base64 — used by some compression libraries that skip the GZIP framing overhead.
- LZ-String (Base64): LZ-String compressed with Base64 output — the most common LZ-String variant, used by localStorage compression libraries like lz-string and localforage-lz-string.
- LZ-String (UTF-16 / URI): Alternative LZ-String encodings — UTF-16 for compact string storage and URI-safe Base64 for URL query parameter encoding.
Important Limitations
The string decompressor works with text-based compressed strings. It cannot decompress binary files (use the GZIP Decompressor or ZIP Extractor for those). LZ-String decompression requires the input to have been compressed with the matching LZ-String variant — mixing variants (e.g. using Base64 decoder on a UTF-16 string) will produce garbled output or an error. If decompression fails, try a different algorithm variant.
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Frequently Asked Questions About String Decompressor
A string decompressor reverses the compression process — it takes a compressed, encoded string and restores it to the original readable text. Our free string decompressor online supports GZIP+Base64, DEFLATE+Base64, and all three LZ-String variants (Base64, UTF-16, URI). It runs entirely in your browser using the native DecompressionStream API and a pure-JS LZ-String implementation.
GZIP+Base64 is the most common format — try it first for API payloads, HTTP responses, and server-generated compressed strings. LZ-String Base64 is used by localStorage compression libraries. LZ-String URI is used for URL query parameter state encoding. LZ-String UTF-16 is used for compact in-memory string storage. If you are unsure, try each algorithm until the output looks correct.
Yes, completely. The string decompressor runs entirely in your browser. Your compressed payload is never uploaded to any server and never leaves your device. All decompression happens locally with complete privacy guaranteed — safe for API tokens, session data, and confidential payloads.
Yes — 100% free, forever. No signup, no account, no premium tier, no payload size limits, and no ads. Decompress unlimited strings completely free.
LZ-String is a JavaScript compression library based on the LZ-based compression algorithm. It is widely used for compressing data before storing it in localStorage (which has a 5–10 MB limit), encoding state in URL query parameters, and compressing cookie values. The string decompressor supports all three LZ-String output formats: Base64, UTF-16, and URI-safe Base64.
This usually means the selected algorithm does not match the compression format of your input. Try a different algorithm — for example, if GZIP+Base64 fails, try LZ-String Base64. Also check that the input string is complete and not truncated. Some Base64 strings require padding characters (=) at the end.
No. The string decompressor is designed for text-based compressed strings. For binary .gz files, use the GZIP Decompressor tool. For ZIP archives, use the ZIP File Extractor. For .tar.gz archives, use the TAR.GZ Extractor.
DEFLATE is the underlying compression algorithm. GZIP is DEFLATE plus a file format wrapper (header, checksum, metadata). If your Base64 string was compressed with GZIP (the most common case), use GZIP+Base64. If it was compressed with raw DEFLATE without the GZIP wrapper, use DEFLATE+Base64. The string decompressor handles both formats.
There is no artificial size limit. The practical limit depends on your browser's available memory. For typical use cases — API payloads, localStorage values, URL state — the string decompressor handles them instantly. Very large compressed strings (several MB) may take a moment to process.