RSA and ECDSA key generator
Generate RSA (2048, 3072 or 4096 bits) and ECDSA (P-256, P-384) key pairs right in your browser, in PEM format, for testing, JWT, signatures and encryption.
How to useGenerate a public and private key pair
Available in: 
RSA and ECDSA key generator: what it is for
Choose the algorithm and generate a key pair with the browser's Web Crypto API. The public key comes out in SPKI format (BEGIN PUBLIC KEY) and the private key in PKCS#8 (BEGIN PRIVATE KEY), ready for JWT RS256 or ES256, digital signatures and encryption tests. The keys can be copied or downloaded as .pem files.
The keys are generated in your browser and are not sent to any server.
How to use
- Choose RSA or ECDSA and the size.
- Click Generate keys.
- Copy or download the public and private keys.
When to use it
- Signing JWT tokens in a test environment.
- Setting up integrations that ask for a public key.
- Studying asymmetric cryptography.
Frequently asked questions
Are the keys generated securely?
Yes. They are created in your browser by the Web Crypto API, with the system's cryptographic random number generator. Nothing is sent to servers.
Which format is used?
The public key comes out as PEM in SPKI format (BEGIN PUBLIC KEY) and the private key in PKCS#8 (BEGIN PRIVATE KEY), accepted by OpenSSL, Node.js, Java, Python and most libraries.
Can I use them for SSH?
PEM PKCS#8 is not the same format as OpenSSH's id_rsa file. To access servers, generate the key with ssh-keygen on your computer instead. These keys work well for JWT, signatures and testing.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.