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ARJ to RAR Converter

Convert ARJ 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 an ARJ file?

The ARJ (Archived by Robert Jung) format is a lossless compressed archive container developed by Robert K. Jung in 1991 for MS-DOS environments, utilizing the LZ77-based Lempel-Ziv-Storer-Szymanski (LZSS) algorithm and Huffman coding. Prominent during the Bulletin Board System (BBS) era for its superior compression ratios compared to PKZIP 1.0, the format supports multi-volume spanning, 32-bit Cyclic Redundancy Checks (CRC-32) for data integrity, and password protection. The file structure consists of a main header followed by compressed file data blocks, making it capable of storing directory trees and file attributes compatible with 16-bit and 32-bit architecture.

How to open an ARJ file

Modern operating systems such as Windows 11, macOS, and Linux do not provide native kernel-level support for decoding legacy ARJ binaries. To extract these archives, users must utilize third-party file compression utilities that include the necessary decompression libraries. 7-Zip is the standard recommendation for Windows environments due to its broad codec support, while macOS users should utilize The Unarchiver; Linux users can access content via the command-line arj or unar packages found in standard repositories.

ARJ Technical Info

Full Name
Archived by Robert Jung
Developed By
Robert K. Jung
Initial Release
1991
MIME Type
application/x-arj

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 ARJ to RAR in seconds

Every ARJ 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.

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Developer API

Convert ARJ to RAR via API

Automate ARJ 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": "arj-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.arj

# 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.