Comparison of API simulation tools

The tools listed here support emulating^[1] or simulating APIs and software systems. They are also called^[2] API mocking tools, service virtualization tools, over the wire test doubles and tools for stubbing and mocking HTTP(S) and other protocols.^[1] They enable component testing in isolation.^[3]

In alphabetical order by name (click on a column heading to sort by that column):

Name	FOSS	Free	Supported protocols and APIs	Has a GUI	Scriptable/Programmable	Docker support	Cloud offering
API Simulator	No; Proprietary[4]	Yes	HTTP/2 with TLS ALPN; HTTP/2 with prior knowledge; HTTP/2 upgrade from HTTP/1.1; HTTP/1.x with and without TLS/SSL; HTTP(S)	Yes[5]	Yes[6][7]	Yes[8]	No
apiUi [9]	Yes; GPL v3.0[10]	Yes	HTTP(S); STOMP, WSDL; Swagger; OpenAPI; Cobol	Yes[11]	Yes[12]	Yes[13]	No
Beeceptor [14]	No; Proprietary[15]	Yes (Free plan)	HTTP1.1; HTTP2; HTTP(S); SOAP, MITM/Proxing; Swagger; OpenAPI; TLS 1.2; XML; Local tunneling	Yes	Yes[16]	Yes	Yes
Camouflage	Yes; MIT[17]	Yes	HTTP(S), HTTP/2 gRPC, Websockets, Thrift	Yes[18]	Yes[19]	Yes[20]	No
Castle Mock	Yes; Apache 2[21]	Yes	HTTP(S)	Yes	Yes	Yes	No
Charles Proxy	No; Proprietary[22]	No	HTTP(S)	Yes	No	No	No
Ekko Proxy	No; Proprietary	Yes (non commercial use)[23]	HTTP(S), JDBC; WSDL, Swagger, OpenApi, JWT.	Yes[24]	Yes (Scriptable)	Yes	No
HAM	Yes; MIT	Yes	HTTP(S), SOAP, MITM/Proxing, Swagger, XML, JSON, Jackson-Smile, Brotli, Record, Replay, Automatic tests, Schema verification, JDBC, MongoDb	Yes (Web)	Yes (Dynamic Javascript and Java Plugins)	Yes	No
Hoverfly	Yes; Apache 2[25]	Yes	HTTP(S)	Yes	Yes	Yes	Yes [26]
HTTP Toolkit	Yes; AGPL[27]	Yes (Hobbyist Edition)[28]	HTTP(S)	Yes	No	No	No
Int4 IFTT	No; Proprietary	No	HTTP(S), Middleware virtualization: SAP Process Orchestration, SAP Intelligent Suite, Dell Boomi, Software AG Webmethods, SAP IDOCs	Yes	Yes	No	No
Karate	Yes; MIT[29]	Yes	HTTP(S), Java interop[30]	No	Yes[30]	No	No
Microcks	Yes; Apache 2[31]	Yes	HTTP(S), SOAP, gRPC, GraphQL, AsyncAPI[32]	Yes	Yes	Yes	No
Mockadillo	No; Proprietary	No	HTTP(S)[33]	Yes	Yes	No	Yes
Mocklets	No; Proprietary[34]	Yes	HTTP(S)	Yes	No	No	Yes [35]
Mockoon	Yes; MIT[36]	Yes	HTTP(S)[37]	Yes	Yes	Yes [38]	No
MockServer	Yes; Apache 2[39]	Yes	HTTP(S)	Yes[40]	Yes	Yes	No
mock.qa	No; Proprietary	Yes (Free plan)[41]	gRPC, gRPC-web, HTTP/1.x, HTTP/2[42]	Yes[43] (Web)	Yes[44][45] (Scripting language,[46] Request matching,[47] Response templating,[48] Data generation,[49] Stateful scenarios[50])	No	Yes
Mountebank	Yes; MIT[51]	Yes	HTTP(S), TCP, SMTP[52]	No	Yes[53]	Yes[54]	No
NetOcean	No; Proprietary	No	Web Services Protocols: HTTP, HTTPS, HTTP2, REST, SOAP, Hessian Others: IMAP, FTP, DNS, XML, JSON, WebSocket ESB / Middleware Protocols, TIBCO JMS Database Protocols: JDBC Proprietary: TCP, UDP Platforms: TIBCO-EMS, IBM-MQ, Kafka SOA Protocols: SOAP, HTTP, XML, REST SMS Gateway Providers: SMTP, POP3 Bill Payments Services: Gift card- PINPAD, AJB	Yes	Yes	Yes	Yes
Parasoft Virtualize	No; Proprietary	Yes (Community Edition)[55]	AMQP, FIX, FTP, HTTP(S), ISO 8583, JMS, JDBC, MQ, MQTT, .NET WCF, RabbitMQ, SAP, TCP/IP, etc.[56]	Yes	Yes	Yes[57]	Yes
Postman	No; Proprietary	Yes (Free Edition)[58]	HTTP(S)	Yes	Yes (JSON Examples)	No	Yes
ProxyMan	No; Proprietary	Yes,[59] (Limited)	HTTP(S), Websockets	Yes	Yes[60]	No	No
QuickMocker	No; Proprietary	Yes (Free Subscription)[61]	HTTP(S)	Yes	Yes[62]	No	Yes
Rapidmock	No; Proprietary[63]	Yes (Free Edition)	HTTP(S)	Yes	No	No	Yes
Requestly	Yes; GPL v3.0[64]	Yes[65]	HTTP(S)	Yes	Yes	No	Yes[66]
sMockin	Yes; Apache 2[67]	Yes	HTTP, Websockets, Server Side Events, plus tools for real time monitoring & live response modification	Yes	Yes	Yes	No
Smocker	Yes; MIT[68]	Yes	HTTP(S)[69]	Yes	Yes	Yes	No
SmartMock.io	No; Proprietary[70]	Yes [71]	HTTP(S)	Yes	Yes	No	Yes
Specmatic	Yes; MIT[72]	Yes	HTTP(S), Swagger, OpenAPI, WSDL, Kafka, AsyncAPI, GraphQL, gRPC	No	Yes	Yes	No
simulado	Yes; MIT[73]	Yes	HTTP(S)	No	Yes	Yes	Yes
SoapUI MockServer	Yes; EUPL[74]	Yes	HTTP(S)[75]	Yes[75]	No[75]	No[75]	No[75]
Speedscale	No; Proprietary	Yes, (Free Trial)[76]	HTTP(S), gRPC, GraphQL webservices, Message queues, OSS Databases[77]	Yes	No, Not required. Traffic recording-based[78]	Yes	Yes
Stoplight	Yes; Apache 2[79]	Yes (Free Edition)[80]	HTTP(S) and generate mocks directly from OpenAPI	Yes	Yes	Yes	Yes
TPM-Proxy	Yes; MIT	Yes	Direct Wire Protocol implementation: HTTP(S), SOAP, MITM/Proxing, OpenAPI, XML, JSON, Jackson-Smile, Brotli, MongoDb, Postgres, MySQL, AMQP 091, MQTT, REDIS, Record, Replay, Modify	Yes	Yes (Java Plugins)	Yes	No
Traffic Parrot	No; Proprietary[81]	No;[82]	HTTP(S) including REST and SOAP gRPC JMS (ActiveMQ TCP, ActiveMQ AMQP 1.0, Azure AMQP 1.0, RabbitMQ AMQP 0.9.1, IBM® WebSphere MQ 7.5+) Native IBM® WebSphere MQ 7.5+ Thrift AMQP 1.0 File transfers over a filesystem Amazon Simple Queue Service (SQS) Azure Service Bus AMQP 1.0 [83] In beta:[84] FIX, FAST, FIXatdl, SWIFT, MQTT, SonicMQ, Kafka, CORBA, FTP, SFTP, .NET WCF, RMI, MTP, TIBCO EMS, CICS, SAP RFC, JDBC, Mongo, Databases, OFX, IFX, RIXML, AS2, Amazon Simple Notification Service (SNS), AWS IoT Message Broker, XMPP, Google Cloud Messaging (GCM), Azure Event Grid, Azure Event Hubs, STOMP, Avro, HTTP/2 (HTTP2), LWM2M, CoAP (Constrained Application Protocol), ZeroMQ, Broker-J (BrokerJ), Qpid, QUIC and gQUIC (Google QUIC)	Yes[81]	Yes[85]	Yes[81]	Yes[86][81]
tweak	No; Proprietary	Yes	HTTP(S)	Yes	No	No	No
Tricentis API Simulation	No; Proprietary	Yes(Free Edition)[87]	Http(s), AmazonSqs, AMQP, AzureServiceBus, Files, IbmMQ, Kafka, RabbitMQ, Solace	Yes [87]	Yes [87]	Yes [88]	Yes [87]
Wilma	Yes; GPL v3.0[89]	Yes [90]	HTTP(S)	Yes	Yes	Yes [91]	No
WireMock	Yes; Apache 2[92]	Yes	HTTP(S), gRPC, GraphQL	Yes	Yes	Yes	Yes [93]
WireMock.Net	Yes; Apache 2[94]	Yes	HTTP(S)	No	Yes	Yes [95][96]	No
Wiresham	Yes; Apache 2[97]	Yes	TCP	No	Yes	No	No

See also

• Test double
• Service virtualization