Open .cer Files Online — Free CER Viewer
Open CER File Online — Free & Instant
No signup required. Works in your browser.
📁 Drag & drop your file here
or click to browse • Max 100MB
✅ Free • ⚡ Instant • 🔒 Secure • 💻 No install
What Is a .cer File?
A .cer file is a security format known as CER. CER is a certificate file in DER or Base64 format. This format is created by Various and is widely used by security analysts.
CER files contain structured security data that requires compatible software to open. With OpenAnyFile, you can inspect and validate .cer files directly in your browser without installing any software.
How to Open .cer Files Online
- Visit OpenAnyFile CER page
- Drag and drop your .cer file onto the upload area, or click "Browse" to select it
- OpenAnyFile automatically detects the CER format using magic byte analysis
- View, analyze, and inspect and validate your file contents in the browser
- Optionally convert to PEM, CRT, DER or download
Software That Opens .cer Files
.cer files are primarily created by Various. In the security space, you may encounter .cer files from third-party tools, online converters, or export functions. Regardless of the source, OpenAnyFile handles them all.
Open .cer on Different Platforms
- Windows: Use the original software or upload to OpenAnyFile for instant access
- macOS: Preview may not support .cer — use OpenAnyFile as a universal viewer
- Linux: Open-source alternatives exist, or use OpenAnyFile in any browser
- Mobile (iPhone/Android): OpenAnyFile works on all mobile browsers
Common .cer File Problems
Format varies — can be binary or text.
Other common issues include: your OS not recognizing the file extension, the file appearing corrupted after download, or lacking the required software. OpenAnyFile bypasses all these issues with universal format detection.
Convert CER to Other Formats
CER files can be converted to 3 formats including PEM, CRT, DER.
Related Security Formats
If you work with .cer files, you may also encounter these security formats:
- 1Password Vault (opvault) — Open & convert opvault files online
- ACME Account (acme.json) — Open & convert acme.json files online
- AGE (.age) — Open & convert .age files online
- Age Encrypted (age) — Open & convert age files online
- ANSIBLE_VAULT (.yml) — Open & convert .yml files online
- ASC (.asc) — Open & convert .asc files online
- Authorized Keys (authorized_keys) — Open & convert authorized_keys files online
- Bitwarden Export (bitwarden.json) — Open & convert bitwarden.json files online
- ClamAV (.cvd) — Open & convert .cvd files online
- CRL (.crl) — Open & convert .crl files online
Popular CER Conversions
Frequently Asked Questions
What is a .cer file?
A .cer file is a security format called CER. CER is a certificate file in DER or Base64 format.
How do I open a .cer file without installing software?
Upload your .cer file to OpenAnyFile. Our browser-based tool instantly detects and displays it — no downloads needed.
What program creates .cer files?
.cer files are typically created by Various.
Can I convert .cer to another format?
Yes. OpenAnyFile converts .cer to PEM, CRT, DER.
Is it safe to open .cer files online?
Yes. OpenAnyFile processes files in a secure, isolated environment. Files are automatically deleted and all transfers use HTTPS.
Can I open .cer on my phone?
Yes. OpenAnyFile works on all mobile browsers including iPhone and Android.