File format and archive decoders
File format decoders read a file's internal structure — compressed streams, archive directories, database headers, font tables and PDF object graphs — so you can see what a file contains and whether it is well-formed without opening it in its native application.
File Format & Archives tools
Gzip / Zlib / Deflate Decompressor
Inflate gzip, zlib and raw deflate streams in the browser.
Tar / Zip / 7z Parser
List entries and headers inside archive files.
Bzip2 / LZMA Decoder
Decompress bzip2 and LZMA/XZ streams.
Parquet / Avro Header Decoder
Read Parquet and Avro file headers and schemas.
SQLite Header Decoder
Decode a SQLite database header and page layout.
Windows Registry Hive Decoder
Parse .DAT/.REG registry hive structures.
TrueType / OpenType Inspector
Read font tables, names and glyph counts.
PDF Structure Parser
Walk PDF objects, streams and the xref table.
Which decoder do I need?
- Bytes starting 1f 8b, or an H4sI… Base64 string
- Gzip / Zlib / Deflate Decompressor
- A .zip, .tar or .7z file
- Tar / Zip / 7z
- A .db or .sqlite file
- SQLite Header
- A PDF whose objects you want to inspect
- PDF Structure
About file format & archives decoding
Every binary format starts with a signature and a header that describe the rest of the file: 1f 8b for gzip, PK\x03\x04 for Zip, 'SQLite format 3' for SQLite and %PDF for PDF. Reading those structures is how you identify a mystery file, recover data from a damaged one or check what a document really contains.
The gzip, zlib and raw deflate decompressor is live today and runs entirely in your browser. The archive, database, font and PDF inspectors are on the roadmap, and each page already documents its format's layout.
Frequently asked questions
How do I identify an unknown file type?
Look at its first few bytes, the magic number. 1f 8b is gzip, 50 4b 03 04 is Zip (and therefore also .docx, .xlsx and .jar), 25 50 44 46 is PDF and 89 50 4e 47 is PNG. The hexdump viewer shows them.
Why does a Base64 string start with H4sI?
H4sI is how the gzip magic bytes 1f 8b 08 look after Base64 encoding. Paste it straight into the gzip decompressor, which accepts Base64 input and inflates it in one step.
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