Windows
Compatible Applications
What is a .cram file?
File Extension Details
The CRAM file format is a highly efficient, compressed data format used primarily in the field of bioinformatics and genomics for storing biological sequences aligned to a reference genome. Developed by the European Bioinformatics Institute (EBI) and maintained as a standard by the Global Alliance for Genomics and Health (GA4GH), CRAM was designed as a more compact successor to the BAM (Binary Alignment Map) format. The primary innovation of CRAM is its use of reference-based compression; instead of storing every nucleotide in a sequence read, it only records the differences between the read and a specific reference sequence. This approach, combined with advanced entropy coding techniques, allows CRAM files to be significantly smaller than their BAM counterparts, often achieving a 30-60% reduction in storage requirements. This is crucial for large-scale sequencing projects where data storage costs are a major concern. CRAM supports both lossless compression, which preserves all original data including quality scores, and lossy compression modes that can further reduce size by binning quality scores. It also supports random access through the use of companion index files, typically ending in the .crai extension, making it suitable for high-performance computing environments and cloud-based genomic analysis.
Software Compatibility
Programs that can open and work with .cram files
macOS
Compatible Applications
Linux
Compatible Applications
Mobile
Mobile Applications
Frequently Asked Questions
About .cram files
To open a .cram file, you need compatible software. Here are some options:
- IGV (Integrative Genomics Viewer)
- SAMtools (via WSL)
- SAMtools
- JBrowse 2 (Web-based)
To convert a .cram file to another format, you can:
- Use compatible software Many programs that open .cram files also allow you to save or export them to different formats.
- Try online conversion services: Websites like Zamzar, CloudConvert, or Online-Convert allow you to convert files between different formats without installing software.
- Specialized conversion tools: Search for '.cram converter' to find tools specifically designed for this file type.
- Verify the file extension is correct:
- Update your software:
- Try alternative software:
- Check for file corruption:
Like any file type, .cram files can be safe or potentially risky depending on their source:
- Always scan files with antivirus software before opening
- Keep your operating system and applications updated.
- Be especially cautious with executable file types
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