API Simulator Features

Feature-rich and quite capable, API Simulator can be an indispensable tool in your development and testing toolbox. The Standalone API Simulator's features below are not roadmap items - they are available out-of-the-box, right now.

Run API Simulator on local workstations or dedicated servers. No need for an application server or external database.
Runs anywhere Java™ runs. Which is a very large set of platforms...
Multi-Instance Capable
Run multiple instances on the same host. Each instance can be for the same or a different simulation.
No Coding Required
Intuitive, easy to learn and use YAML-based DSL (Domain Specific Language) for configuration-driven simulations.
Extensible by Scripting
Script anything not built-in yet. Out-of-the-box support for JavaScript and Groovy.
API Polyglot
API Simulator can simulate APIs exposed over both text and binary protocols.
Web APIs
Current focus is on HTTP 1.1 and HTTP 1.0 APIs. ReST, SOAP, RPC style APIs... Using JSON, XML, or different payload...anything based on HTTP.
TLS (HTTPS) Support
Support for TLS/SSL using X.509 certificate and private key in PEM format, run-time generated self-signed cert, or Java KeyStore in JKS Format.
Callable as HTTP/S Proxy
Do not change the application/service configuration but, instead, configure the HTTP client to use API Simulator as HTTP/S proxy.
Callable Directly
Change the configuration of the application/service to call the API Simulator's endpoint instead that of the actual API.
Default Simulated Output
Designate default output to return when the input can't be recognized. For example, returning "404 Not Found" response with static or dynamic body.
Forwarding Unrecognized Requests
Unmatched requests can be forwarded to their actual destination and the live responses passed back to the client instead of returning a default simulated output.
Static Stubs/Mocks
Returning static, fixed response for a given request - often times called API mock or stub - is easy with API Simulator.
Dynamic Output
The power of output dynamically changing even for the same input - date and time values, computations, parameters from the request, lookups in external data store...
Extensive Input Matching
Multi-key input matching by URI (route), URI path pattern, any URI part, HTTP Method, HTTP Header fields, and values from the payload.
Simula Template Engine
Simula - a flexible templating system developed for API Simulator - drives dynamic response rendering.
Dynamic Input Parameters
Configure dynamic parameters from the request to use in constructing the response.
Randomly Generated Values
Test Data Management via randomly generated numbers, dateime values, tokens from a pattern...
CSV Parameters Source
CSV (comma-delimited value) files as source for parameters to include in dynamic output.
SQL Parameters Source
Relational database as the source and SQL statements to retrieve parameters to include in dynamic output.
Large Content Download
Simulations that stream large content, even bigger than 2GB (!), with only few MB of memory.
Latency Simulation
Configurable delay in sending output to simulate latency and API slowness.
HTTP API Fidelity
Support for HTTP protocol-specific features like chunked transfer encoding even for dynamic output, compressed output content (gzip, deflate), full support for "keep alive" connections, custom HTTP Header fields...
API Recorder
Capture raw HTTP traffic and save it into files with API Recorder. The recordings can greatly ease the modelling of API simulations.

It gets even better - fully functional API Simulator is free!


There is more, and more is coming. We will gladly look into any suggestions what features to add or how to improve API Simulator.

Meanwhile, give API Simulation Modeler a try - a browser-based UI for modeling API simulations. Stop muddling through config files or writing code to mock APIs!


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

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


Happy Simulations!

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