About CertView
CertView is a free certificate viewer built for a simple job: you have a certificate file — from a server, a CA, a device vendor, or your own test PKI — and you want to know exactly what is inside it before you deploy it.
What it does
- Decodes X.509 certificates from .pem, .crt, .cer, .der and .pfx/.p12 files, including multi-certificate chain files.
- Shows subject, issuer, serial number, signature algorithm, validity with days remaining, SAN entries, public key details, every extension with plain-language labels, and SHA-256 / SHA-1 fingerprints.
- Verifies signature chains when you load a leaf certificate together with its CA.
- Checks whether a private key file matches a certificate, without displaying the key.
- The companion certificate generator creates custom CA, server and client certificate sets locally in the browser, with PEM, DER and PFX export.
Why local-only matters
Certificates for internal systems, medical devices and test environments should not be uploaded to random websites. CertView therefore parses everything in your browser with JavaScript — no file ever leaves your device. Close the tab and nothing remains.
The viewer is a single static page, so it also works saved offline. For how-to material, see the guides. CertView is part of the ToolHub toolbox, a categorized collection of free online tools.
关于 CertView
CertView 是一个免费的证书查看器，为一件简单的事而做：你有一张证书文件——来自一台服务器、一个 CA、设备厂商，或你自己的测试 PKI——你想在部署它之前，确切知道里面装了什么。
它能做什么
- 解码 .pem、.crt、.cer、.der 和 .pfx/.p12 文件里的 X.509 证书，包括包含多张证书的链文件。
- 展示主体、颁发者、序列号、签名算法、带剩余天数的有效期、SAN 条目、公钥详细信息、每一个扩展（附通俗易懂的文字说明），以及 SHA-256 / SHA-1 指纹。
- 当你把叶子证书和它的 CA 一起载入时，核对签名链。
- 核对一个私钥文件是否与一张证书配对，且不显示私钥内容。
- 配套的证书制作工具可以在浏览器本地创建自定义的 CA、服务端和客户端证书成套文件，并支持导出 PEM、DER 和 PFX。
为什么只在本地运行很重要
内部系统、医疗设备和测试环境用的证书，不应该被上传到随便什么网站。CertView 因此用 JavaScript 在你的浏览器里解析一切——没有任何文件会离开你的设备。关掉标签页，什么都不会留下。
这个查看器是一个单文件静态页面，所以保存下来离线也能用。操作方法类的材料，见指南。CertView 是 ToolHub 工具箱的一部分，那是一个按分类整理的免费在线工具集合。