Mocking tools stand in for a backend that is unfinished, offline or billed per call. The field runs from one JSON file served over HTTP, through desktop designers and hosted endpoints with request quotas, to servers for gRPC and AsyncAPI.
This ranking puts small independent projects first, then weighs setup hours, cost growth and exports.
Vendors can pay for more visibility on this website, for example a higher place in a ranking or more room on a page. Commercial relationships can also affect which products we feature and how prominently. Every vendor link is marked the same, whatever the arrangement behind it. How that works.
In short
What API mocking tools software does
API mocking software returns scripted responses for HTTP and other protocols, so testers and developers run integrations against simulated services before the real backend exists or while it is unreachable.
Our order comes from five tests, taken in turn: effort to set up, what you really pay, what happens to your data on the way out, how locked in you are, and the intended customer. One rule sits on top of those tests: places 1 to 3 go to challengers, vendors outside the best-known brands in a category, wherever the category has them; the established names follow from place 4 in their ranked order. Our how we work page explains the choice of these five and why we give no mark out of ten.
Desktop mock designer with a CLI and Docker image, MIT licensed
Ranked #1 of 13 in Best API Mocking Tools in 2026.
Published pricingElsewhere
Mockoon bills in licence slots, and a slot is spent either on a named user seat or on a mock instance running at the same moment, which turns parallel test jobs into a budget line.
Enterprise adds invoicing or purchase orders, a four-business-hour support response and an optional managed cloud with an availability SLA. Pro is self-hosted by default. The desktop app, the @mockoon/cli package and the mockoon/cli image all come from the MIT-licensed repository.
What stands out
Desktop designer
MIT licence
Licence slots
Where it costs you
The Team plan has a five-licence minimum and annual billing only, so a two-person team cannot buy it.
Each licence covers one user seat or one concurrently running mock instance, so CI parallelism uses up slots.
Right for
Developers designing mocks on a desktop, then running the same files in CI
Wrong for
Pairs wanting to buy a paid plan monthly
Not stated by the vendorPublished per-licence rate for the Team plan, annual billing only; Enterprise on request; 14-day trial of Pro
Apache-licensed mock engine for Java and .NET, plus a cloud edition
Ranked #2 of 13 in Best API Mocking Tools in 2026.
Self-hostablePublished pricingElsewhere
The engine and the cloud are separate purchases of effort. Embedding the Apache-2.0 engine in Java or .NET tests costs nothing in licences, while WireMock Cloud adds a shared workspace, stateful mocking, CSV or database import and CI hooks.
For AI coding agents the home page names Agent Skills and a remote MCP server. Runner executes the same simulations locally or in private infrastructure, which matters when the hosted route is ruled out. Pricing text was not readable.
What stands out
Apache-2.0
Java and .NET
Cloud and Runner
Where it costs you
The pricing page returned 404, so no plan names, prices or limits could be checked.
The pages read state no country or registered address for WireMock Inc.
Right for
Java teams embedding a mock engine in tests who may want a hosted workspace
Wrong for
Buyers needing cloud plan limits before talking to anyone
Not stated by the vendorEngine to self-host under Apache-2.0; cloud edition shows a Free forever banner, plan details not shown
Hosted mock endpoints for REST, GraphQL, SOAP and gRPC, tiered by requests
Ranked #3 of 13 in Best API Mocking Tools in 2026.
Self-hostablePublished pricingElsewhere
Beeceptor's ladder is easy to read: starter, Individual, Team and Scale, each with a request ceiling, a mock-rule count and a CRUD-object count. Mutual TLS, CI/CD integration and unlimited team members arrive at Team, while Scale adds a forward proxy and configuration snapshots.
Extra Scale traffic costs $40 per additional million requests. Enterprise is the only route to running Beeceptor in your own cloud or VPC. Its operating company and country are not named on the site.
What stands out
Hosted endpoints
Request-based tiers
Self-hosted Enterprise
Where it costs you
The starter tier keeps public endpoints only, and unclaimed endpoints are deleted after 30 days.
Volume decides the tier, so a high-traffic test suite pushes the bill up through the request caps.
Right for
Teams wanting mock URLs running in minutes with no server to maintain
Wrong for
Teams whose test suites send millions of requests
Not stated by the vendorPublished tiers sized by monthly requests, from a zero-cost starter to a million-request Scale tier; Enterprise quoted; 10-day Team trial
CNCF incubating mock and test server for REST, AsyncAPI, gRPC and GraphQL
Ranked #4 of 13 in Best API Mocking Tools in 2026.
Open sourcePricing on requestElsewhere
Microcks covers more protocols than most entries here: the site names OpenAPI, AsyncAPI, gRPC, GraphQL and SOAP. It works from API assets you already hold, mocking them and running contract checks against them, with a CLI for CI pipelines.
The licence is Apache-2.0, with the microcks GitHub organisation as owner. Because no plans or prices appear anywhere, the cost is engineering hours for deploying the images, not a subscription.
What stands out
CNCF incubating
AsyncAPI and gRPC
Apache-2.0
Where it costs you
The site names no commercial offering, so paid support or a hosted service has to come from elsewhere.
Container images on Quay.io point to a container platform, which is more setup than a single binary.
Right for
Platform teams mocking event-driven and synchronous APIs from the same specifications
Wrong for
Solo developers wanting a mock running in one command
Not stated by the vendorApache-2.0 project; the site mentions no commercial offering, plans or prices
Self-hosted HTTP, HTTPS and gRPC mocking, proxying and recording
Ranked #5 of 13 in Best API Mocking Tools in 2026.
Open sourceSelf-hostablePricing on requestElsewhere
Packaging is the strong point: npm, Maven Central, PyPI, RubyGems, Go, NuGet, crates.io, Packagist and Homebrew are all listed, so a test suite in nearly any language can start it.
It records real traffic as well as serving scripted answers. What is missing is any statement of ownership beyond a personal copyright holder, any named licence, or any route to commercial help, which a procurement checklist usually asks for.
What stands out
Mock and proxy
Eight client languages
Docker and Helm
Where it costs you
The licence is never named on the site, and the GitHub page returned 404 when we read it.
No commercial support or paid option is mentioned, so every incident stays with your own staff.
Right for
Polyglot teams that need one mock and proxy server reachable from many test languages
Wrong for
Organisations that require a vendor contract and support terms
Not stated by the vendorNo plans or prices appear on the site; run it yourself from Docker, JAR, Helm or Testcontainers
YAML and JSON mocks served on one port, managed on another
Ranked #6 of 13 in Best API Mocking Tools in 2026.
Pricing on requestElsewhere
The two-port layout keeps test control apart from the traffic under test: scripts post mocks to 8081 while the application under test calls 8080. The reset endpoint makes each test start clean, and the web interface shows what is registered.
MIT licence, owner smocker-dev on GitHub, documentation at smocker.dev. The repository describes no hosted or paid product, which keeps the footprint small but leaves hosting entirely to you.
What stands out
MIT licence
YAML and JSON mocks
Built-in web UI
Where it costs you
Only HTTP is described, so teams mocking gRPC or event streams need another tool.
The repository mentions no hosted version, so sharing mocks across a team means running the container yourself.
Right for
Test suites that load mocks through an API and wipe them between runs
Wrong for
Teams mocking anything beyond plain HTTP services or event streams
Not stated by the vendorMIT-licensed Docker image or release tarball; no hosted or priced product is mentioned
Java stub server covering HTTP/1.1, HTTP/2 and WebSockets
Ranked #7 of 13 in Best API Mocking Tools in 2026.
Pricing on requestElsewhere
Protocol breadth sets stubby4j apart from the simpler HTTP stubs: HTTP/2 and WebSockets sit next to classic HTTP/1.1, and fault injection lets a test simulate a misbehaving service.
Record and replay can capture real exchanges, and regex matching shapes which request gets which stub. It is built and published by one maintainer on the site, with no company, prices or support tiers, so expect to rely on the documentation.
What stands out
MIT licence
HTTP/2 and WebSockets
Fault injection
Where it costs you
It depends on a Java runtime of 1.8 or higher unless you choose the Docker image.
A single named maintainer is listed and no paid support exists, so continuity rests on one person.
Right for
Java shops testing HTTP/2 or WebSocket clients against faulty stub responses
Wrong for
Teams wanting a hosted dashboard shared by non-developers
Not stated by the vendorMIT licence; JAR from Maven Central and Docker Hub images, with no prices on the site
Hosted simulation platform built on an Apache-licensed framework
Ranked #8 of 13 in Best API Mocking Tools in 2026.
Pricing on requestElsewhere
Two things carry the name: an Apache-licensed framework that you build and run yourself, and Hoverfly Cloud, a lightweight hosted platform sitting on it. The framework path costs no licence and starts from a binary or the repository Dockerfile.
The hosted path is described by a throughput claim of 2,000 requests per second and little else we could verify. Ownership is split across a SpectoLabs repository, an iOCO Solutions README and a Cloud copyright line.
What stands out
Apache License 2.0
Hosted simulation
Single binary
Where it costs you
Plans, prices, billing basis and any trial were not visible, so the hosted cost cannot be compared.
The page names no parent company or country, only an ioco.uk logo beside the Hoverfly Cloud copyright line.
Right for
Teams already comfortable with a Go-style single binary and wanting a hosted option
Wrong for
Buyers who must see a price list before shortlisting
Not stated by the vendorCloud plans, prices and trial were not readable on the home page; the framework is Apache License 2.0
Mock APIs defined in YAML or a web editor, hosted or local
Ranked #9 of 13 in Best API Mocking Tools in 2026.
Published pricingElsewhere
Mocki keeps the choice narrow: one Starter plan billed monthly with prioritised support and a monitoring dashboard, plus a free API editor for quick test endpoints.
Mocks can be written as YAML, so definitions can sit in version control, and the local CLI works without a connection. The footer credits Sveten, and neither the operating company nor the country is named on the pages read. Currency is not printed beside the price.
What stands out
YAML or web editor
Offline CLI
Single plan
Where it costs you
The only listed plan caps traffic at 1,000 requests a day, with no larger tier shown.
No ongoing no-cost plan is described, only a 7-day trial and an editor for simple endpoints.
Right for
Small teams wanting hosted mocks with simulated delays and errors
Wrong for
High-volume test automation or teams needing several price tiers
Not stated by the vendorOne published monthly plan with a daily request cap; 7-day trial and a no-cost editor for simple endpoints
Fake REST API from one JSON file in under thirty seconds
Ranked #10 of 13 in Best API Mocking Tools in 2026.
Pricing on requestElsewhere
The appeal is speed: one file becomes a working REST API, with operators for greater than, not equal, list membership and case-insensitive match, plus sorting and paging by query parameter. A JSON-based _where parameter handles harder filters.
That makes it good for prototypes and UI work. Request matching, fault injection and recorded traffic are not in the description, so it stays a fixture server rather than a service simulator.
What stands out
MIT licence
db.json routes
Filtering and paging
Where it costs you
Routes follow the file structure, so scenario-style responses that depend on request content are not described.
No hosted or paid product exists, and sponsorship tiers are the only commercial mention.
Right for
Front-end developers needing a CRUD backend from a plain JSON file today
Wrong for
Contract testing or request matching by method and path
Not stated by the vendorMIT licence; the README lists sponsorship tiers and describes no hosted product
OpenAPI-driven mock server and validation proxy from the Stoplight stable
Ranked #11 of 13 in Best API Mocking Tools in 2026.
Self-hostablePublished pricingElsewhere
Prism assumes an API description exists: it reads OpenAPI or Postman files and answers from them. The CLI is open source and costs nothing; the hosted route costs money by team size, from a one-user starter through Basic, Startup and Pro Team, each paid tier with a 14-day trial.
Stoplight Studio, a visual OpenAPI designer with integrated mocking, is described as free. Buying hosted mocks therefore means buying a design platform too.
What stands out
OpenAPI mocking
Validation proxy
Stoplight platform
Where it costs you
Hosted mocking is tied to Stoplight platform plans, which price by user count and step up sharply.
The pricing page footer names SmartBear Software and no country, so ownership is not fully explained.
Right for
Teams keeping OpenAPI as the source of truth, with mocks generated from it
Wrong for
Teams without OpenAPI or Postman files to start from
Not stated by the vendorSelf-hosted CLI under Apache-2.0; hosted mocking comes with Stoplight platform plans published per month, one zero-cost single-user plan
Fixed-response endpoint and request inspector built by Zuplo
Ranked #12 of 13 in Best API Mocking Tools in 2026.
Published pricingElsewhere
Mockbin is the lightest option in this ranking: no account, a fixed response, and a view of incoming requests. Uploading an OpenAPI 3.x file makes the response follow the description rather than a hand-typed body.
The page calls the tool fully free and links to zuplo.com and the zuplo/mockbin source repository, but states no operating company, country or usage ceiling. That is acceptable for a one-off webhook check, not for a test suite your release depends on.
What stands out
No sign-up
OpenAPI 3.x upload
Request inspector
Where it costs you
The site states no limits, retention period or plan, so reliability under load is unverified.
Bin IDs live in the browser, so clearing storage may lose the link to your bins.
Right for
Developers needing a throwaway endpoint to catch and inspect a webhook call
Wrong for
Teams needing stateful mocks, shared workspaces or an audit trail
Not stated by the vendorDescribed by the site as fully free, with no sign-up; no plans, limits or trial are stated
Contract-testing platform with managed and self-hosted Pact options
Ranked #13 of 13 in Best API Mocking Tools in 2026.
Self-hostablePublished pricingElsewhere
Pactflow checks that two services agree on an interface, using bi-directional contract testing, and records verification results. The plan table runs from Starter, which is $0 and counts 10 AI-generated tests a month, to Team at roughly $115 a month with yearly billing and Enterprise by quote.
A Self-Hosted Pact Broker column lists unlimited integrations and webhooks but no AI tests, teams or SSO. Ranked last because it complements mocking rather than providing it.
What stands out
Contract testing
Bi-directional
Pact broker
Where it costs you
Our sources describe contract testing and a broker, not a mock or stub server, so it complements a mocking tool.
Starter limits of 2 integrations and 2 webhooks are quickly outgrown by several services.
Right for
Teams already mocking elsewhere who need consumer and provider contracts verified
Wrong for
Anyone seeking a mock server to run tomorrow morning
Not stated by the vendorPublished Starter and Team plans, Starter at no cost; Enterprise quoted; 14-day Team trial
API mocking software returns scripted responses for HTTP and other protocols, so testers and developers run integrations against simulated services before the real backend exists or while it is unreachable. Work through these questions in order; they separate the products better than a feature matrix does.
01
Start with pricing transparency
6 vendors on this page sell by quote, while 7 publish a pricing model you can read today: Mockoon, WireMock, Beeceptor, Mocki, Prism, Mockbin, Pactflow.
02
Ask which country the contract runs through
Check the vendor's home market (Elsewhere 13), because that is where subpoenas and data requests arrive first, whatever region holds your files.
03
Decide if open source matters
2 of these are open source: Microcks, MockServer. Hosting one yourself trades a subscription for maintenance.
Setup time for API mocking tools: json-server, Mockoon and Mockbin
The first ninety days divide tools by how much typing stands between you and a running endpoint. json-server turns a db.json file into a REST API, Mockbin gives a fixed-response URL with no sign-up, and Mockoon runs from a desktop window or an npm command. Microcks and WireMock Cloud cost more hours, because container images, workspaces and specification imports come first.
Time spent here repays itself only when mocks must survive beyond a prototype. Write down who maintains the definitions, since a mock that nobody updates silently drifts from the real service and then passes tests it should fail. Count the hours to get one realistic scenario working, not a hello-world response.
Time one error scenario with a delay, not a happy-path response
Check whether definitions are plain files you can keep in git
Name the person who updates mocks when the real API changes
Real price: Mockoon licence slots against Beeceptor request tiers
Mocking tools bill on three different meters, and the cheapest one depends on your test pattern. Mockoon counts licence slots shared between user seats and running instances, so many parallel CI jobs consume slots. Beeceptor counts requests, from 50 a day per endpoint on the starter tier to a million or more on Scale, so a chatty suite hits the cap.
Mocki publishes a single plan with 1,000 requests a day. Engines such as WireMock, MockServer and Smocker cost no licence but cost hosting and upkeep. Model a normal week of test runs before choosing, then check what the next tier adds, because mutual TLS, custom domains and audit logs often arrive only on a higher level.
Estimate requests per test run and multiply by runs per day
Count concurrent mock instances in your busiest CI hour
List which security features sit on the tier above
Exit and licences across WireMock, Microcks and Prism
Leaving a mocking tool is easy when definitions are files in a documented format. Prism reads OpenAPI and Postman files, Microcks works from OpenAPI, AsyncAPI, gRPC and GraphQL assets plus Postman files, and Smocker takes YAML or JSON, so the source material survives a switch. Hosted editors are different: stub definitions kept only in a web workspace need an export route you should test before signing.
Read the licence line too. WireMock, Microcks and Prism state Apache-2.0, Mockoon, Smocker and stubby4j state MIT, while MockServer calls itself open source without naming a licence on its site. A named licence is a precondition for legal sign-off, and a missing one deserves a question to the maintainer before adoption.
Export one mock definition and import it into a second tool
Find the licence text in the repository, not the marketing page
Confirm the file format is documented and not proprietary
Choosing among API mocking tools and Pactflow-style contract platforms
Mocking, simulation and contract testing overlap but are not the same job. WireMock, MockServer and Hoverfly stand in for a service and can proxy or record traffic. json-server fakes a data store. Pactflow verifies that consumer and provider agree, using Pact contracts, and its sources describe no stub server, so it complements a mock rather than replacing one.
Protocol coverage is the other split: stubby4j names HTTP/2 and WebSockets, MockServer names gRPC, and Microcks names AsyncAPI. Decide first whether you need a fake, a simulator or a contract check, then match the protocols your services speak. Buying a contract broker to solve a mocking problem is a common and costly mismatch.
List the protocols your services use beyond plain HTTP
Decide between a data fake, a simulator and a contract check
Test proxy and record mode against one real dependency
What goes wrong most often when buying API mocking tools software
Choosing a hosted endpoint tool such as Beeceptor or Mocki without estimating requests per day, then discovering the cap during a release week.
Treating a fixture server such as json-server as a service simulator, and finding that conditional responses and fault injection are missing.
Counting only user seats for Mockoon when each running mock instance in CI also takes a licence slot.
Assuming an engine with no price, like MockServer or Microcks, has no cost, when hosting and maintenance fall on your own team.
07
Frequently asked questions
8 answers
What is the best API mocking tools in 2026?
Mockoon takes first place among the 13 we reviewed. Mockoon is MIT licensed and arrives as a desktop application, an npm command line tool and a Docker image, so one set of mock definitions runs on a laptop and in a pipeline.
Team needs at least five licences on annual billing, and each licence is a slot for one user seat or one running instance, so parallel CI jobs consume slots. The Pro trial lasts 14 days.
Which API mocking tools publish their pricing?
Published pricing exists for 7 products on this page:
Mockoon: Published per-licence rate for the Team plan, annual billing only; Enterprise on request; 14-day trial of Pro.
WireMock: Engine to self-host under Apache-2.0; cloud edition shows a Free forever banner, plan details not shown.
Beeceptor: Published tiers sized by monthly requests, from a zero-cost starter to a million-request Scale tier; Enterprise quoted; 10-day Team trial.
Mocki: One published monthly plan with a daily request cap; 7-day trial and a no-cost editor for simple endpoints.
Prism: Self-hosted CLI under Apache-2.0; hosted mocking comes with Stoplight platform plans published per month, one zero-cost single-user plan.
Mockbin: Described by the site as fully free, with no sign-up; no plans, limits or trial are stated.
Pactflow: Published Starter and Team plans, Starter at no cost; Enterprise quoted; 14-day Team trial.
The remaining 6 sell by quote.
Is there a free API mocking tool?
No, every product on this page is paid.
Where are these API mocking tool vendors established?
In 1 countries across 1 regions: Elsewhere 13.
Mockoon: Not stated by the vendor.
WireMock: Not stated by the vendor.
Beeceptor: Not stated by the vendor.
Microcks: Not stated by the vendor.
MockServer: Not stated by the vendor.
Smocker: Not stated by the vendor.
Stubby4j: Not stated by the vendor.
Hoverfly: Not stated by the vendor.
Mocki: Not stated by the vendor.
json-server: Not stated by the vendor.
Prism: Not stated by the vendor.
Mockbin: Not stated by the vendor.
Pactflow: Not stated by the vendor.
Which API mocking tools are open source?
Microcks, MockServer.
Which API mocking tools can you host yourself?
WireMock, Beeceptor, MockServer, Prism, Pactflow. The other 8 are hosted by the vendor only.
What should you use instead of Mockoon?
WireMock and Beeceptor are the next two on this page. WireMock is for Java teams embedding a mock engine in tests who may want a hosted workspace; Beeceptor is for teams wanting mock URLs running in minutes with no server to maintain.
Who should not buy Mockoon?
Pairs wanting to buy a paid plan monthly. The Team plan has a five-licence minimum and annual billing only, so a two-person team cannot buy it..
Vendors who think their API mocking tools product should be here can tell us about it: what it does, who it is for. The call is ours, and software advice sets out what being listed means.
