PEM Formatter
Format PEM certificates, public keys, private keys, CSRs, and multiple PEM blocks with safer label checks and 64-character line wrapping.
Formatted PEM Output
Private Key Safety Note
PEM formatting runs locally in your browser and does not upload your content. Still, private keys are sensitive. Avoid pasting production private keys on shared devices, public computers, or untrusted browser sessions.
Formatting PEM Certificates and Keys Safely
PEM files are text blocks that usually contain certificates, public keys, private keys, CSRs, CRLs, or other cryptographic material. A PEM block has a BEGIN line, a Base64 body, and a matching END line. Many servers and libraries expect the Base64 body to be wrapped in clean lines.
This formatter preserves the PEM label, checks matching BEGIN and END boundaries, removes extra whitespace inside the Base64 body, and wraps the output into standard 64-character lines. It also supports multiple PEM blocks, such as certificate chains.
The tool does not guess a missing label. If you paste bare Base64 text without BEGIN and END lines, it asks you to add the correct PEM boundaries instead of inventing a private-key or certificate label.
How to Use the PEM Formatter
- Paste a full PEM block with BEGIN and END lines.
- Click Format PEM.
- Review label warnings, Base64 warnings, and private-key cautions.
- Copy the formatted PEM only after checking that the label is correct.
Common Use Cases
- Formatting public keys and private keys copied from dashboards.
- Cleaning SSL and TLS certificate blocks before server setup.
- Checking BEGIN and END label mismatches.
- Formatting certificate chains that contain multiple PEM blocks.
- Preparing JWT signing keys for local development.
- Removing broken whitespace from copied PEM values.
- Keeping Base64 body lines readable and consistent.
Example PEM Structure
Input can be messy:
-----BEGIN PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtestdata... -----END PUBLIC KEY-----
Formatted output keeps the same label:
-----BEGIN PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtestdata... -----END PUBLIC KEY-----
What This Formatter Checks
- Matching labels: BEGIN CERTIFICATE must close with END CERTIFICATE, not a different label.
- Base64 body shape: The tool checks for invalid characters and suspicious Base64 length.
- Multiple blocks: Certificate chains and other repeated PEM blocks can be formatted together.
- No trust validation: Formatting does not prove that a certificate is trusted or that a private key matches a certificate.
Frequently Asked Questions
What is PEM format?
PEM is a text encoding style commonly used for certificates, public keys, private keys, CSRs, CRLs, and related security files. The content is usually Base64 data wrapped by BEGIN and END lines.
Why are PEM lines wrapped at 64 characters?
Standard PEM generators wrap the Base64 body into 64-character lines, except for the final line. This improves compatibility with tools that expect traditional PEM text formatting.
Does this tool change the key or certificate data?
It removes whitespace from the Base64 body and rewraps the text. It does not decrypt, regenerate, or intentionally change the encoded object.
Can this verify a certificate chain?
No. This is a formatter. It does not validate trust chains, expiry, hostname matching, issuer trust, revocation, or key usage.
Are PEM values uploaded anywhere?
No. Formatting happens locally in your browser.