BIT File

What are BIT files and how to open them

Are you having problems opening a BIT file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BIT files.

What is a BIT file?

BIT files have multiple uses, and Bit Archiver compressed archive is one of them. Read more about the other uses further down the page.

Bit Archiver compressed archive

These BIT files are compressed files created by Osman Turan. BIT gives a high compression ratio with acceptable speeds.

How to open BIT files

Important: Different programs may use files with the BIT file extension for different purposes, so unless you are sure which format your BIT file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested three different BIT openers which you will find listed below.

Last updated: August 24, 2026

All known file formats using extension .BIT

While Bit Archiver compressed archive is a popular type of BIT-file, we know of 3 different uses of the .BIT file extension. Different software may use files with the same extension for different types of data.

Lotus Manuscript Bitmap

Lotus Manuscript Bitmap stores a raster image used inside Lotus Manuscript documents. It was produced by Lotus Manuscript (DOS word processor), intended for embedding bitmapped graphics like charts, diagrams or scanned images into a Manuscript document. It supports simple compression via run-length encoding to reduce file size.

The format is written by Lotus Manuscript and read by it when rendering or printing documents. When a bit-mapped graphic is included in a Manuscript file, the graphic must follow this format or be converted so that Manuscript recognizes the format header and compression style.

These files begin with two bytes: ASCII "BH" (bytes 0x4248) at offset zero. That signature identifies the file as a Lotus Manuscript Bitmap. The format variant is noted as "RLE" in some format listings, indicating that run-length encoded data follows after a header.

Xilinx Bitstream

Xilinx Bitstream files store the complete configuration data required to program a Xilinx (now AMD) FPGA device, defining its logic, circuit routing, I/O settings, and initial contents of internal memory. The format is produced by Xilinx's implementation tools after a design - expressed in hardware description languages or schematic form - is synthesized, placed, and routed. These files are loaded into the FPGA via configuration ports (e.g. JTAG, SPI) or stored in non-volatile memory so that when the device powers up it initializes to the design stored in the bitstream.

Each bitstream file begins with an ASCII-encoded header containing human-readable metadata: the design name, target FPGA part number, build date and time, tool version and sometimes other project identifiers. After that header is a binary payload which encodes the actual configuration frames for the device - the bits that set up logic cells, routing switches, I/Os, and memory initialization. The tools used to generate such files include Xilinx's Vivado suite (command Write-Bitstream) and formerly ISE.

The format supports optional features such as encryption, authentication, and bitstream masking. Encryption methods vary by FPGA family: for example, AES (with modes such as CBC or GCM) and HMAC or RSA-based authentication are supported in newer families. A tool called Bootgen is often used with specially prepared image files (.bif) to produce secure or masked bitstreams.

An internal signature at the beginning helps identify the file format: files begin with a two-byte length and big-endian TLV (Tag-Length-Value) sequence, then a one-byte key such as 0x61 ("a") for design name, followed by other tags ("b" for part name, "c" for date, "d" for time), ending with a tag "e" that precedes the binary payload. One such magic sequence is "00 09 0F F0 0F F0 0F F0 0F F0 00 00 01 61 00 0A …" at offset zero.

Various apps that use files with this extension

These apps are known to open certain types of BIT files. Remember, different programs may use BIT files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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