Free SSL Certificate Converter — PEM to Base64 and Back Online

Convert SSL/TLS certificates between PEM and Base64 (raw) format instantly.
Select the conversion direction, paste your data, and get the result. Everything
runs client-side in your browser — no upload, no account needed, fully private.

via CrtMgr — client-side converter

Two Conversion Modes

PEM → Base64

Extract the raw Base64 body from a PEM-encapsulated certificate. Strips the
-----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- headers and any
whitespace, leaving you with a single continuous Base64 string. This is the
format required by many automation tools, API integrations, and configuration
management systems that expect the DER content without PEM wrapping.

For example, converting a certificate for crtmgr.com from PEM to Base64 gives
you the exact DER bytes encoded as a single line of text — ready to paste into
a Kubernetes Secret, a Terraform variable, or an environment variable in a CI
pipeline.

Base64 → PEM

Wrap a raw Base64 certificate body back into standard PEM format with proper
-----BEGIN CERTIFICATE----- / -----END CERTIFICATE----- headers and
64-character line folding. The tool auto-detects whether the input is a
certificate or a CSR, so the BEGIN/END markers are always correct. If the input
is ambiguous, it defaults to CERTIFICATE.

This is useful when you’ve received a certificate body from an API, a database,
or a configuration file that stored only the Base64 payload, and you need to
write it to a .crt or .pem file that web servers (Apache, Nginx, HAProxy,
Caddy) and load balancers expect.

When Certificate Format Conversion Matters

Working with SSL/TLS certificates across different platforms often requires
switching between PEM and raw Base64:

  • Web servers (Nginx, Apache) expect PEM files with headers and 64-char
    line breaks for ssl_certificate directives.
  • Cloud platforms (AWS Certificate Manager, Azure Key Vault) may require
    the raw body when importing via API or CLI.
  • Kubernetes TLS Secrets store certificates as Base64-encoded data without
    PEM headers — the converter produces exactly that format.
  • Configuration management tools (Ansible, Terraform, Puppet) sometimes
    expect the certificate body as a single-line value in HCL or YAML.
  • Database storage — if you store certificates in a database column, the
    compact Base64 format is often preferred over multi-line PEM.

Supported Certificate Types

The converter works with X.509 certificates, Certificate Signing Requests, and
any other PEM-encapsulated data with standard BEGIN/END markers. It validates
that the Base64 content is syntactically correct before producing output.

Privacy

Conversion is performed entirely in your browser using client-side JavaScript.
No data is ever sent to a server. Production certificates, private PKI material,
and internal CSRs remain completely local.

Rate Limits

There are no limits on conversions. The tool does not call any API — the Base64
encoding and decoding runs directly in your browser.

Related Tools

  • SSL Certificate Decoder — after converting a certificate
    to PEM or Base64, decode it to inspect every field: subject, issuer, SANs,
    public key, extensions, and fingerprint.
  • CSR Decoder — parse a Certificate Signing Request to verify
    its contents before conversion or submission to a Certificate Authority.
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