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CPIO to RAR Converter

Convert CPIO to RAR online for free. Fast, secure, and high-quality conversion with no sign-up or software required.

Free to useNo file stored beyond 1 hourEncrypted over TLS 1.2/1.3No watermarks

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How it works

Three steps to your converted file

Everything happens in your browser tab - upload, pick a format, download. The heavy lifting runs on our servers.

01

Upload your file

Drag and drop, click to browse, or paste a URL. Batches take up to 20 files at once - 230+ input formats across video, audio, image, document, and archive types.

02

Choose an output format

Pick from over a hundred output formats. Filter by category or search by name - every option is open to everyone, no account needed.

03

Convert & download

Hit Convert and grab your download link moments later. Originals are erased when the job completes; results are cleared within about an hour.

What is a CPIO file?

The CPIO (Copy In, Copy Out) format is a binary or ASCII archive file format used predominantly in Unix-like operating systems for backing up and transferring files between disparate systems. Originally defined as part of the Programmer's Workbench (PWB/UNIX) and later standardized in POSIX.1 (IEEE Std 1003.1-1988), CPIO archives store file metadata-including inode numbers, user IDs, and timestamps-alongside the raw data stream. Unlike TAR, CPIO handles non-tape media and special files more robustly but requires specific headers (binary, old ASCII, or new ASCII/CRC) to ensure compatibility across System V and BSD-derived kernels.

How to open a CPIO file

Native extraction of CPIO archives is standard on Linux and macOS distributions via the GNU cpio or pax command-line utilities (e.g., cpio -idv < archive.cpio). For Windows environments, which lack kernel-level support for POSIX archiving tools, users must utilize third-party decompression software such as 7-Zip or PeaZip, which implement the necessary decoders to interpret the CPIO header structures and extract the contained file hierarchy.

CPIO Technical Info

Full Name
Copy In, Copy Out
Developed By
AT&T / Bell Labs
Initial Release
1977
MIME Type
application/x-cpio

What is a RAR file?

RAR (Roshal Archive) is a proprietary archive file format developed by Eugene Roshal that supports data compression, error recovery, and file spanning. It utilizes a variation of the LZSS algorithm with a sliding window size of up to 4 MB (in RAR4) or 1 GB (in RAR5), combined with Huffman coding. Key technical features include support for AES-256 encryption, BLAKE2sp hash algorithms for file integrity, and specialized recovery records that allow for the reconstruction of damaged data. The format structure supports solid archiving, where multiple files are treated as a single continuous data stream to improve compression ratios.

How to open a RAR file

Due to the proprietary nature of the RAR licensing, creating RAR files requires licensed software (WinRAR), though extraction is supported by various free tools. Windows users typically use WinRAR or 7-Zip to extract contents. macOS users can utilize The Unarchiver or Keka. On Linux, the non-free unrar package or the open-source 7z (p7zip-full) package provides extraction capabilities via the command line.

RAR Technical Info

Full Name
Roshal Archive
Developed By
Eugene Roshal
Initial Release
1993
MIME Type
application/vnd.rar

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Why RunConvert

The fastest way to convert any file

Purpose-built for speed, privacy, and breadth of format support.

Convert CPIO to RAR in seconds

Every CPIO to RAR conversion runs on our servers, so your device stays fast and the output quality stays intact.

Fast, cloud-powered

No queue, no waiting. Files are processed on high-performance servers and returned in seconds, even for large files.

Secure & private

Encrypted in transit and never shared with anyone. Uploads are erased the moment your job completes, and results shortly after.

Free - no account needed

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Developer API

Convert CPIO to RAR via API

Automate CPIO to RAR conversions in three steps: create a job, upload your file, then poll for the result.

# 1. Create job
curl -X POST https://api.runconvert.com/v3/jobs \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "tag": "cpio-to-rar",
    "tasks": {
      "upload-file": {
        "operation": "import/upload"
      },
      "convert": {
        "operation": "convert",
        "input": "upload-file",
        "output_format": "rar"
      },
      "export-result": {
        "operation": "export/url",
        "input": "convert"
      }
    }
  }'

# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.cpio

# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$JOB_ID?include=tasks \
  -H "Authorization: Bearer YOUR_API_KEY"

Replace YOUR_API_KEY with your RunConvert API key. Get your free API key at runconvert.com/api.