SSL Certificate Format Converter
Convert SSL/TLS certificates between PEM, DER (binary), and Base64 formats — entirely in your browser, nothing uploaded.
About SSL Certificate Format Converter
SSL/TLS certificates come in several formats. PEM is the most common — a text format using base64 with header/footer lines. DER is a binary encoding of the same data. This tool converts between all three representations without uploading anything to a server.
Format Guide
- PEM — Text format, starts with
-----BEGIN CERTIFICATE-----. Used by Apache, Nginx, and most Unix tools. - DER — Binary format. Used by Java, Windows, and IIS. Same data as PEM but not base64 encoded.
- Base64 — The raw base64 payload of a PEM file without the header/footer lines.
Frequently Asked Questions
Yes. All conversion happens in your browser. No data is sent to any server.
DER certificates typically use the .der, .cer, or .crt file extensions. Note that .crt and .cer can also be PEM format — check the file content to confirm.