API testing tools send requests to an interface and check what returns, from a single manual call to a suite that runs on every commit.
This guide ranks twelve tools on what the first ninety days cost in setup, what the bill becomes once teams, runners and reports are added, how collections leave, and whether the vendor stands alone.
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 testing tools software does
API testing tools send requests to web services, assert on the responses and status codes, and repeat those checks from a desktop client or a build pipeline.
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. Challengers hold places 1 to 3 wherever the category has them. Established brands begin at place 4. Reasons for the choice of tests, and for skipping a score out of ten, can be read on the how we work page.
Prices not shown on the product page; trial and demo offered
—
Large organisations testing many protocols, from Kafka and RabbitMQ to SOAP, that want tests built from recorded traffic.
Small teams that need to see a price and start testing the same afternoon.
We list the country the vendor operates from or contracts through. That is not the same as the hosting region, and any difference is spelled out in the entry.
MIT-licensed API client with Git integration and cheap per-user tiers
Ranked #1 of 12 in Best API Testing Tools in 2026.
Free tierOpen sourcePublished pricingElsewhere
The pricing page shows three tiers. Open Source costs nothing and covers HTTP, REST, GraphQL and gRPC, scripting, code generation and an unlimited collection runner.
Pro and Ultimate add private Git providers, data-driven testing, SSO, audit logs and 24-hour support at Ultimate. Support on the free edition is community only. Terms name Bruno Software, Inc. and a Delaware governing law, but no head office.
What stands out
Open source
Git integration
Per-user tiers
Where it costs you
Data-driven runs need Pro, and report generation is Ultimate only.
The free edition connects only to public Git providers and is limited to two workspaces.
Right for
Developers who want tests stored beside code and a low price per seat
Wrong for
Teams needing reports or private Git hosting without paying
Not stated by the vendorFree open source edition; Pro and Ultimate billed per user annually; 14-day trial of Ultimate
The pricing page offers cloud or self-host. Free gives personal workspaces, collections, pre-request scripts, tests and a collection runner. Business adds team workspaces, shared environments, documentation publishing, mocking and an MCP server.
Enterprise adds identity management and Slack support. The docs say self-hosting Community Edition costs nothing; the on-premise Enterprise Edition is a separate commercial version with priority support. Business also lists an admin dashboard and email support, which the free plan leaves out.
What stands out
Open source
Self-host option
Browser based
Where it costs you
Shared team workspaces and mock servers are in the paid Business plan, not the free one.
SAML SSO, SCIM and audit logs are only in the Enterprise plan or Enterprise Edition.
Right for
Teams that want an open source client they can host themselves
Wrong for
Teams wanting a full test-authoring suite with reports
Not stated by the vendorFree cloud plan; Business and Enterprise billed per user annually; self-host Community Edition free
MIT-licensed test framework for APIs, UI and performance in one runtime
Ranked #3 of 12 in Best API Testing Tools in 2026.
Free tierOpen sourceSelf-hostablePublished pricingNorth America
Karate Labs states that every product runs on your own machines, with nothing hosted and no usage billing. The Free tier includes the open source framework and the Xplorer desktop client.
Pro is priced per user per year, with a saving for annual billing, and adds IDE tooling and Xplorer Premium. Enterprise is a custom annual licence adding API coverage, governance and support SLA. The company is in Wilmington, Delaware.
What stands out
Open source
Test framework
Self-hosted
Where it costs you
Kafka, gRPC and WebSocket tests running in CI require an Enterprise runtime licence.
Debugging and autocomplete in IntelliJ and VS Code sit in the paid Pro tier.
Right for
Engineering teams automating API and UI tests in one codebase
Wrong for
Teams wanting a hosted dashboard for managers and non-technical reviewers
United StatesFree open source core; Pro billed per user annually; Enterprise by annual contract
REST client living inside VS Code and JetBrains editors
Ranked #4 of 12 in Best API Testing Tools in 2026.
Free tierPublished pricingEurope
The vendor says collections and environments are stored locally and are not tied to the account, which keeps export simple.
Starter is a single-user licence paid by card; Business adds centralised billing, invoices and team administration; Enterprise adds offline activation and secrets-manager integration, with audit logs listed as coming soon. Trials are by request and only for business email addresses.
What stands out
Editor extension
Low price
Local data
Where it costs you
The free plan allows 3 collections, 50 requests per collection and 5 imports a month.
Local runner runs are capped per user each month below the Enterprise plan.
Right for
Developers who test APIs from inside their editor all day
Wrong for
Testers who work outside VS Code or JetBrains
IrelandFree plan; Starter, Business and Enterprise billed per user annually; 14-day team trial
Design, debug and test APIs in one shared team workspace
Ranked #5 of 12 in Best API Testing Tools in 2026.
Free tierPublished pricingElsewhere
The billing documentation describes a Free Plan, a Basic plan priced per member per month with a cheaper annual rate, and an Enterprise plan with a 14-day trial that needs no card.
All plans include Mac, Windows, Web and Linux apps. The docs cover SOAP, GraphQL, gRPC, WebSocket, SSE and MCP clients, test scenarios with assertions, SSO and SCIM. Where the company is registered is not stated on the pages read.
What stands out
Free plan
Per-member plans
Spec import
Where it costs you
The pricing page could not be read as text, so exact plan limits need checking in the app.
Monthly billing costs more per member than the annual rate.
Right for
Teams wanting design, mocking and testing in one shared workspace
Wrong for
Buyers who must confirm the contracting company first
Not stated by the vendorFree plan; paid plans billed per member monthly or annually; 14-day trial
Ranked #6 of 12 in Best API Testing Tools in 2026.
Free tierOpen sourcePublished pricingNorth America
The pricing page lists Essentials with unlimited cloud and local projects, end-to-end encryption and 1,000 mock requests a month. Pro adds unlimited users on Git Sync, role-based access and 10,000 mock requests.
Enterprise adds SSO, SCIM, vault integrations and Konnect, and is self-serve up to 50 users. A local-only Scratch Pad is free. Kong says it is headquartered in San Francisco.
What stands out
Git sync
Kong-owned
Open source client
Where it costs you
Git Sync is free only for up to three users; more collaborators need Pro.
Mock server requests are capped monthly, with extra requests billed in blocks.
Right for
Developers wanting a Git-synced client with a CLI for CI
Wrong for
Larger teams wanting free collaboration beyond three people
United StatesFree Essentials plan; Pro and Enterprise billed per user; 14-day Enterprise trial
Hosted API tests and uptime monitors that run after each deployment
Ranked #7 of 12 in Best API Testing Tools in 2026.
Free tierPublished pricingElsewhere
The plans page lists a Personal plan that stays free, and Standard, Startup and Business at flat monthly rates with higher member caps. There is no per-user fee.
You can start from a URL, an API specification or a curl command, sync tests when the specification changes, and trigger runs from a deployment call or GitHub push. Alerts go to Slack. The about page names founders but no location.
What stands out
Hosted
Deployment testing
Flat account fee
Where it costs you
It runs only as a hosted service, so private endpoints must be reachable from the cloud.
Limits fall on retained results, tests and schedule frequency, not on requests, so check each.
Right for
Small teams wanting scheduled checks and post-deploy tests without running servers
Wrong for
Teams that need self-hosting or a local desktop client
Not stated by the vendorFree plan; paid plans at a flat monthly fee per account; one-month trial on paid plans
Long-running open source tool for SOAP and REST test suites
Ranked #8 of 12 in Best API Testing Tools in 2026.
Open sourcePricing on requestNorth America
The SoapUI site presents the open source edition as the starting point for individuals working in a single environment, with REST, SOAP and WSDL testing and API mocking. The GitHub repository carries an EUPL 1.1 licence.
Everything beyond that moves to the commercial ReadyAPI, which offers a 14-day trial. SmartBear's cover page names SoapUI and Swagger as its own products, so support and roadmap are tied to one parent.
What stands out
Open source
SOAP support
SmartBear
Where it costs you
Data-driven testing and automatic test refactoring are not in the open source edition.
Reports are compared by reading logs by hand; there is no native CI integration.
Right for
Testers maintaining SOAP and WSDL services from a single workstation
Wrong for
Teams needing data-driven suites, reports and CI plug-ins
United StatesOpen source edition downloadable; paid ReadyAPI sold separately; 14-day ReadyAPI trial
SmartBear's commercial suite for functional, load and virtual API testing
Ranked #9 of 12 in Best API Testing Tools in 2026.
Pricing on requestNorth America
The ReadyAPI site compares itself with SoapUI Open Source: it supports REST, SOAP, GraphQL, JMS, XML-RPC and MQTT, builds assertions without code, refreshes requests when a specification changes, and stores projects locally or in Git.
Modules are sold as packages. The trial lasts 14 days without a card. SmartBear lists its headquarters in Somerville, Massachusetts, with a European office in Galway.
What stands out
Commercial suite
Load testing
Service virtualization
Where it costs you
Prices were not visible in the pricing page text, which makes budgeting a conversation.
The page speaks of test packages, so confirm which modules each package includes.
Right for
QA teams already on SOAP and REST suites needing data-driven runs
Wrong for
Individual developers wanting a small client with cheap seats
United StatesPackage-based commercial licences; pricing page text shows no figures; 14-day trial
Collaboration-first API platform with a free tier and metered extras
Ranked #10 of 12 in Best API Testing Tools in 2026.
Free tierPublished pricingNorth America
Among the twelve ranked here, Postman covers the most ground: client, specs, mock servers, native Git, a runner and monitoring all appear on the free plan, which allows one user and 1,000 monitored requests.
Team lifts that to unlimited users, 90 days of collection recovery and 10,000 monitored requests. Usage charges sit on top, with cloud load tests priced per virtual-user hour. Budget for seats first, then for load tests and AI credits, and ask sales for Enterprise terms.
What stands out
Collaboration
Metered extras
Large ecosystem
Where it costs you
The free plan seats one user, so any shared work means paying for Team at $19 per user per month.
Cloud performance tests cost $0.04 per virtual-user hour and AI credit overages are pay-as-you-go, so the bill follows usage.
Right for
Teams that want mock servers, monitors and a collection runner under one login and can accept a bill that moves with use.
Wrong for
Buyers who need a fixed yearly figure, or a light client for one developer who never shares collections.
United StatesFree plan; Solo and Team billed annually; Enterprise by contact; usage charges on cloud load tests
All-round test automation studio where API checks sit alongside web and mobile
Ranked #11 of 12 in Best API Testing Tools in 2026.
Free tierPublished pricingNorth America
Here Katalon is a test automation studio in which API checks are one feature next to web, mobile and desktop work, which places it lower for a buyer who wants an API client first. The free download runs locally, with a 30-day trial of paid tiers.
Headless CI needs Runtime Engine add-ons and cloud execution needs TestCloud. Professional adds parallel runs and AI agents; Enterprise adds SSO, SCIM, audit logs and on-premises deployment. Price it per seat plus execution add-ons.
What stands out
Test automation
Per-seat licence
API plus UI
Where it costs you
Free Studio limits static suites to 40 and has no parallel execution.
Professional is $1,800 per seat per year, and CI or cloud runs are further add-ons.
Right for
QA groups that test web, mobile and API in one studio and mostly run checks from a local machine.
Wrong for
Developers who only want to fire and assert on HTTP calls without a wider automation product.
United StatesFree Studio edition; Professional billed per seat annually; Enterprise by custom contract; 30-day trial
SOAtest for codeless enterprise API test creation, security and load checks
Ranked #12 of 12 in Best API Testing Tools in 2026.
Pricing on requestNorth America
SOAtest sits at the enterprise end of this list. It builds codeless tests from recorded traffic or natural language, handles over 120 message formats and protocols, and reuses functional tests for security and performance checks.
It also lists Test Impact Analysis, Change Advisor and CI hooks for Jenkins, Azure DevOps, Bamboo and TeamCity. The company, based in Monrovia, California, has tested software for over 35 years. The trade-off is opacity, since neither pricing nor plan limits are published.
What stands out
Enterprise
Codeless
Service virtualization
Where it costs you
The SOAtest page shows demo and trial buttons but no prices, so budgeting starts with a sales call.
Service simulation is a separate product, Parasoft Virtualize, which is bought on top.
Right for
Large organisations testing many protocols, from Kafka and RabbitMQ to SOAP, that want tests built from recorded traffic.
Wrong for
Small teams that need to see a price and start testing the same afternoon.
United StatesPrices not shown on the product page; trial and demo offered
API testing tools send requests to web services, assert on the responses and status codes, and repeat those checks from a desktop client or a build pipeline. Rather than compare features, settle the following points one after another.
01
Start with pricing transparency
Only 9 of the 12 print a price; 3 quote per organisation. Comparable without a sales call: Bruno, Hoppscotch, Karate, Thunder Client, Apidog, Insomnia, Assertible, Postman, Katalon.
02
Weigh the vendor's home jurisdiction
Check the vendor's home market (North America 7, Elsewhere 4, Europe 1), because that is where subpoenas and data requests arrive first, whatever region holds your files.
03
Decide if open source matters
5 of these are open source: Bruno, Hoppscotch, Karate, Insomnia, SoapUI. Hosting one yourself trades a subscription for maintenance.
API testing tools: what the free client does not run
Almost every tool here has a free entry point, and the gaps sit in what runs unattended. Bruno keeps its collection runner unlimited but puts data-driven runs in Pro and reports in Ultimate. Thunder Client caps the free plan at three collections and fifty requests each. Insomnia's Essentials plan limits Git Sync to three users and meters mock requests.
Hoppscotch keeps shared workspaces for Business, and Katalon's free Studio lacks parallel execution. Postman's free plan covers one user. SoapUI Open Source leaves out data-driven testing entirely. List what your suite needs on day one, such as CSV-driven cases, CI runs, mocks and a report, then find the lowest tier that includes all of them rather than comparing headline prices.
Write down the data-driven, mock and report features your suite uses
Check the per-month limits on runner runs and mock requests
Run your own largest collection through the free tier before paying
Where collections live: Git files, vendor cloud or local disk
Exit is easiest where tests are files you already control. Bruno lists native Git integration, though its free edition connects only to public providers. Insomnia's Git Sync is free for three users, and Thunder Client says collections stay on your machine and are not tied to the account. Hoppscotch can be self-hosted under MIT, so the server is yours too.
Postman collections live in its cloud workspace, with recovery windows of one day on Free and ninety days on Team. Apidog and Assertible are hosted workspaces with Postman import or specification sync. Before choosing, export a real collection and import it into a second tool to find out what is lost, usually scripts and environments.
Export one real collection and import it elsewhere as a trial
Ask where environment secrets are stored and who can read them
Check whether Git sync works with private repositories on your plan
Frameworks versus clients: Karate, SoapUI and ReadyAPI
A client is built for sending requests by hand; a framework is built to run thousands of checks in a pipeline. Karate and ReadyAPI are the second kind, and they price differently. Karate's core is MIT licensed and self-hosted, but Kafka, gRPC and WebSocket runs in CI need an Enterprise runtime licence. ReadyAPI is sold in packages, with a 14-day trial and no figures visible in the page text.
SoapUI Open Source is the free base for SOAP-heavy shops. Katalon sits between the two: a free desktop Studio, with unattended execution sold as separate add-ons. Decide first whether testers or developers will write the suite, because that, more than price, decides between Karate's code and ReadyAPI's codeless assertions.
Decide whether developers or QA staff will write the suite
Ask which protocols run in CI and under which licence
Confirm how many parallel runners a pipeline needs
Seat pricing against flat pricing for test suites
Most tools here charge per user: Bruno, Hoppscotch Business, Insomnia Pro, Thunder Client Business, Postman Team, Katalon Professional and Karate Pro. Assertible is the exception, with one monthly fee per account and member caps instead. That difference matters when many people only read results. A team of five developers and five reviewers pays for ten seats on a per-user model, while one Assertible Startup plan allows ten members for a single monthly fee.
Postman also meters cloud load tests, and Katalon's free Studio needs add-ons for headless runs. Count writers and readers separately, ask whether viewers are free, and get a written quote from Parasoft before assuming a price, since its product page shows none. Compare the totals only after adding the extras each plan needs.
Count people who author tests apart from people who only read results
Ask whether viewers and reviewers need paid seats
Add usage charges such as cloud load tests or runner add-ons
What goes wrong most often when buying API testing tools software
Choosing on the free tier's feature list, then finding that data-driven runs, reports or private Git sit in a paid plan.
Treating a request client as a test framework, and discovering later that nothing runs headless in the build pipeline.
Storing the only copy of a suite in a vendor cloud workspace without ever testing an export to another tool.
Counting only the people who write tests and forgetting reviewers, who may need paid seats on per-user tiers.
07
Frequently asked questions
8 answers
What is the best API testing tools in 2026?
Bruno leads our ranking of 12. Bruno Software, Inc. sells one product, a desktop API client whose core carries the MIT licence. The free edition includes the collection runner without a cap, but data-driven runs sit in Pro and report generation in Ultimate.
Free-tier Git is limited to public repositories, and the vendor does not state where it is based, so check the contract entity before buying.
Which API testing tools publish their pricing?
The ones that do, with the model each states:
Bruno: Free open source edition; Pro and Ultimate billed per user annually; 14-day trial of Ultimate.
Hoppscotch: Free cloud plan; Business and Enterprise billed per user annually; self-host Community Edition free.
Karate: Free open source core; Pro billed per user annually; Enterprise by annual contract.
Thunder Client: Free plan; Starter, Business and Enterprise billed per user annually; 14-day team trial.
Apidog: Free plan; paid plans billed per member monthly or annually; 14-day trial.
Insomnia: Free Essentials plan; Pro and Enterprise billed per user; 14-day Enterprise trial.
Assertible: Free plan; paid plans at a flat monthly fee per account; one-month trial on paid plans.
Postman: Free plan; Solo and Team billed annually; Enterprise by contact; usage charges on cloud load tests.
Katalon: Free Studio edition; Professional billed per seat annually; Enterprise by custom contract; 30-day trial.
Everything else on the list is priced on request.
Is there a free API testing tool?
Bruno, Hoppscotch, Karate, Thunder Client, Apidog, Insomnia, Assertible, Postman, Katalon have a free plan or free self-hosted edition.
Where are these API testing tool vendors established?
Vendor countries on this page, North America 7, Elsewhere 4, Europe 1:
Bruno: Not stated by the vendor.
Hoppscotch: Not stated by the vendor.
Karate: United States.
Thunder Client: Ireland.
Apidog: Not stated by the vendor.
Insomnia: United States.
Assertible: Not stated by the vendor.
SoapUI: United States.
ReadyAPI: United States.
Postman: United States.
Katalon: United States.
Parasoft: United States.
Which API testing tools are open source?
Bruno, Hoppscotch, Karate, Insomnia, SoapUI.
Which API testing tools can you host yourself?
Hoppscotch, Karate. The other 10 are hosted by the vendor only.
What should you use instead of Bruno?
Hoppscotch and Karate are the next two on this page. Hoppscotch is for teams that want an open source client they can host themselves; Karate is for Engineering teams automating API and UI tests in one codebase.
Who should not buy Bruno?
Teams needing reports or private Git hosting without paying. Data-driven runs need Pro, and report generation is Ultimate only..
We rank 12 API testing tools products on this page. If we missed one, its maker can write to us about its purpose and customers. We pick what gets added; the terms of a listing are set out under software advice.
