RSA Key Generator - TestMu AI (Formerly LambdaTest)

What is the RSA Key Generator?

The RSA Key Generator is a free online tool that produces an RSA key pair you can use for asymmetric cryptography. RSA is one of the most widely deployed public-key algorithms, used in SSH login, TLS certificates, JWT signing, and document signing. A key pair has two parts that work together: a public key you can share freely and a private key you must protect.

The generator builds both keys locally from a secure random source and outputs them in PEM, the Base64 text format wrapped in BEGIN and END lines. You can use the public key to encrypt data or verify a signature, and the private key to decrypt that data or create a signature. The two are mathematically linked, so only the matching private key can undo what the public key protects.

How to use the RSA Key Generator?

Generating a key pair takes only a few seconds and needs no software install. Follow these steps:

• Choose a key size: Select a key size such as 2048 or 4096 bits. Larger keys are stronger but take longer to generate and verify.
• Generate the key pair: Click generate and the tool creates a matching public and private key in your browser using a cryptographically secure random source.
• Copy or download the keys: Copy each key or download it as a PEM file. Keep the private key secret and share only the public key.
• Use the keys: Use the pair for SSH, JWT signing, TLS, or encryption tests, pairing the public key for encryption or verification with the private key for decryption or signing.

Is it safe to generate RSA keys online?

This is the right question to ask before generating any key, and the answer depends entirely on where the key is created. Here is how this tool keeps your keys safe:

• Browser-Based Generation: Both keys are created locally in your browser, so the private key is produced on your own machine and not on a remote server.
• No Upload, No Logging: All processing happens in your browser. No data is uploaded, and the keys are not stored or logged anywhere.
• Verifiable Privacy: You can open your browser developer tools and confirm that no network request carries the keys while you generate them.
• Secure Randomness: Generation draws on your browser's cryptographically secure random number generator, which is the same class of source trusted libraries use.
• Your Responsibility After Generation: Once generated, protect the private key. Do not email it, commit it to a repository, or paste it into untrusted sites.

Use cases of RSA key pairs

RSA key pairs show up across development, operations, and testing. The generator gives you a fast pair for each of these tasks:

• SSH Access: Use the public key on a server and the private key on your client to log in without passwords.
• JWT Signing: Sign tokens with the private key and verify them with the public key, a pattern you can prototype quickly with our JWT Generator.
• TLS and Certificate Testing: Generate keys to experiment with certificate signing requests and TLS handshakes in a test environment.
• Encryption Exercises: Encrypt a sample message with the public key and decrypt it with the private key to learn how asymmetric cryptography behaves, and explore related hashing with the SHA256 tool.

This generator is maintained by TestMu AI (formerly LambdaTest), the team behind a unified testing platform, so it is shaped by a security-first approach to the keys developers and testers rely on. For production secrets, many teams still prefer a local OpenSSL workflow, and that is a reasonable choice.

Frequently Asked Questions (FAQs)

Is it safe to generate RSA keys online?

It is safe when the tool generates keys in your browser and sends nothing to a server, which is how this generator works. Your private key is created locally and never transmitted, so it stays on your machine the entire time.

What is the difference between 2048-bit and 4096-bit RSA keys?

A 2048-bit key is the common minimum and is fast to use. A 4096-bit key is stronger and better for long-lived data, but it is slower to generate and verify. Most production systems pick 2048 or 4096 based on that trade-off.

Are my keys stored on a server?

No. Both keys are generated in your browser and are not logged or uploaded. You can confirm this in your browser developer tools by checking that no request sends the keys anywhere while you generate them.

What key size should I use in 2026?

Use 2048 bits as a practical minimum and 4096 bits for data that must stay secure for many years. Both are widely accepted by certificate authorities and SSH, so choose based on how long the key must remain trustworthy.

What is the difference between the public and private key?

The public key can be shared and is used to encrypt data or verify signatures. The private key must stay secret and is used to decrypt data or create signatures. Together they form one mathematically linked pair.

What is PEM format?

PEM is a Base64 text encoding wrapped in BEGIN and END header lines, which makes keys easy to copy and paste. It is the most widely supported format across SSH, OpenSSL, and most libraries, so it is a safe default.

Should I use RSA or ECDSA?

RSA is widely supported and a solid default, especially for legacy systems. ECDSA keys are smaller and faster for similar strength, so prefer ECDSA for new TLS or SSH setups when every system in the chain supports it.

Can I generate RSA keys offline?

Yes. Because generation runs in the browser, the page works after it has loaded even without a connection. For maximum assurance with production secrets, many teams still generate keys with a local OpenSSL install.