API Simulator 1.10 Release

March 19, 2022

We are excited to announce API Simulator version 1.10!


  • Added support for mTLS (aka mutual TLS, two-way TLS, two-way SSL). If configured, API Simulator will require client authentication during the TLS/SSL handshake trusting either all client certificates or only those signed by specific Certificate Authorities (CAs).
  • TLS versions 1.0, 1.1, and 1.3 are now always enabled in addition to the previously default version 1.2. It will be up to the client to negotiate a version. Nowadays TLS 1.0 and 1.1 are considered insecure but there are still API servers that support them and clients that do not “speak” TLS 1.2 or TLS 1.3.
    NOTE: TLS 1.3 will be enabled only if it is supported by the JDK.
  • Added support for “file” as source for callbacks’ request body. See also this GitHub issue.
  • Loading the configuration for a Callback will now fail when API Simulator detects that the host in the callback URI may be containing scheme (http/https), authority/user info, port number, path, query parameters, or fragment. See also this GitHub issue.
  • Enhanced the HTTP and HTTPS Proxy configurations to allow scheme – “http” or “https” – to be included. Before, the presence of scheme was a cause for misconfiguration.
  • Upgraded various dependencies, including Apache Log4j 2.
  • Fixed possible memory leaks in edge cases when a client unexpectedly closes the connection.
  • Fixed a bug that was preventing API Simulator from starting on Windows when the log output was set to go to stdout.
  • Fixed “Unsupported class file major version 61” error when using JDK 17.
  • Fixed a problem with the “not equals” matching operation.

As usual, the documentation has more details.

We invite you to learn more about API Simulator, download and install it, and run the examples included in the download. Why not even create API simulations to help your own testing and development?

Let us know what you think at [contact at APISimulator.io]. Many thanks for your interest and support!

Happy API Simulating!