SSL-certificaatviewer

Overview

See what's inside an X.509 certificate. Drop in PEM text or a binary DER file and you get the validity dates and whether it's valid today, then subject, issuer and every alternative name. Below that are the key type and size, serial number, and SHA-1 and SHA-256 fingerprints. It reads certificates but doesn't check trust chains, revocation or hostnames. Everything stays in your browser.

Checking expirySee a certificate's dates before a deployment and whether it's valid today.
Sorting a CA bundleRead the subject and issuer of each unlabelled file to tell the leaf, intermediate and root apart.
Checking hostnamesMake sure the alternative names cover every hostname before you install the certificate.
Quick handoffsRead a certificate's scope, issuer and expiry without installing OpenSSL or looking up a command.
Matching fingerprintsCompare the SHA-1 or SHA-256 fingerprint with what your CA or monitoring shows to confirm it's the same certificate.

Set

Beveiligingstools 26

Neighbours

01 AES Bestand & Tekst Encryptor 02 Base64 Decoderen 03 Base64 Coderen 04 CSR Generator 05 DER naar PEM Converter 06 Hash Generator

Specification

Command: security.ssl_certificate_viewer
Set: Security
Input: text
Output: —
Max. bestand: no limit
Batch: single file

Runtime

Engine: WebCrypto · OpenPGP.js
Threads: single
Isolated: —
WebGPU: —
Memory: —

Transport 0 B

Your file is opened, worked on and saved inside this tab. This tool has no upload step, so your file has nowhere else to go.

Keys

Zoeken: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/

How it works

Drop or paste it

PEM text with its BEGIN and END lines, or a binary DER file. It's read in your browser, not uploaded.

See if it's valid today

The dates and current state come first, then subject and issuer, then every alternative name in its own scrollable list.

Check the details

Key type and size, serial number, and SHA-1 and SHA-256 fingerprints to match against your CA or monitoring.

Frequently asked

What certificate formats are supported?

PEM text with its BEGIN and END lines, and binary DER files such as .der, .cer and .crt. No conversion needed. If a PEM file holds several certificates, you see each one.

Can I check whether a certificate is valid?

You see the validity window and whether today falls inside it. There is no revocation check, no hostname check and no trust-chain check.

Is it safe to paste certificates here?

Yes. The certificate is read in your browser, and nothing is uploaded or stored. So you can read an internal certificate without handing it to anyone.

Does this show the certificate chain?

No, the viewer doesn't build or check chains. It does show the issuer name and authority key identifier, which let you work out by hand which certificate signed which.

Why is my certificate showing as expired?

Today falls outside its not-before and not-after dates. Those dates are exact moments in time, so a certificate can show as expired here before a server in another time zone notices, or the other way round.

Keys

Zoeken: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/