Postman is the best AI tool for API testing: it combines an API Client, Collection Runner, monitors and an AI unit test generator, with Solo at $9/mo billed annually. Keploy is #2 and generates tests from OpenAPI or Postman collections and real traffic, and Apidog is #3 with a free plan for up to 4 users.
Developers who want free schema-driven fuzzing in CI
Pick by what you want
Best overall
Postman
Best test generation from traffic
Keploy
Best value
Apidog
Best for enterprise QA
ReadyAPI
Best free fuzzing
Schemathesis
The ranking
1
Postman
Answrs VerdictThe most complete platform for API testing.
Price: Free $0/mo; Solo $9/mo billed annually; Team $19 per user/month billed annually; Enterprise by contacting salesAI credits: Solo includes 400 AI credits a month and Team 400 AI credits per user a monthTesting tools: Collection Runner, Performance Testing, Monitors, Webhook Testing, Functional Testing and Data-Driven TestingAI: Agent Mode automates API workflows with native AI, and an AI unit test generator is listed among its toolsClient: The API Client sends requests, inspects responses and debugs any API
Postman bundles the API Client with Collection Runner, Performance Testing, Monitors, Webhook Testing, Functional Testing and Data-Driven Testing. Agent Mode automates API workflows with native AI, and an AI unit test generator is listed among its tools. Free is $0/mo, Solo is $9/mo billed annually with 400 AI credits a month, and Team is $19 per user/month billed annually.
Go ifTeams that want one platform for API requests, test runs, monitors and AI help
Skip ifYou want a fully open-source tool
Why #1 over #2: It covers more testing types than Keploy, whose Pro plan is $19/user/mo plus usage.
2
Keploy
Answrs VerdictThe best test generator from real traffic.
Price: Playground is free forever; Pro is $19/user/mo plus additional usage; Enterprise is by contactTest generation: Generates API tests from OpenAPI or Postman collections, and AI expands edge cases automaticallyTraffic replay: Captures requests and dependency calls with eBPF without application code changes, then replays them as tests and mocksOpen source: Its core local record-and-replay platform is open source under the Apache 2.0 licenseCI: Tests run locally or in CI/CD pipelines to catch response, schema, contract and performance regressions
Keploy generates API tests from OpenAPI or Postman collections and uses AI to expand edge cases. It also captures requests and dependency calls with eBPF without code changes and replays them as tests and mocks. The Playground is free forever, Pro is $19/user/mo plus additional usage, and the core is open source under Apache 2.0.
Go ifTeams that want tests generated from real traffic and API specs
Skip ifYou prefer a manual request-by-request client
Why #2 over #3: It builds tests from real traffic, which Apidog does through specs.
3
Apidog
Answrs VerdictThe best-value all-in-one platform.
Price: Free $0 per user/month for up to 4 users; Basic $9, Professional $18 and Enterprise $27 per user/month billed annuallyTrial: Paid plans start with a 14-day free trialAI testing: Lists AI-generated test cases and visual orchestration with loops and branching for integration testsSpec-driven: Requests, mocks, tests and published docs stay linked to the same OpenAPI definitionScale: Used by 700K+ developers at 50K+ companies, with a 4.8/5 G2 rating
Apidog links requests, mocks, tests and docs to one OpenAPI definition and lists AI-generated test cases and visual orchestration with loops and branching. Free is $0 per user/month for up to 4 users; Basic is $9, Professional $18 and Enterprise $27 per user/month billed annually, with a 14-day free trial.
Go ifSmall teams that want design, mocking, testing and docs in one low-cost tool
Skip ifYou need a vendor with a long enterprise track record
Why #3 over #4: Its $9 Basic plan and free tier for 4 users cost far less than ReadyAPI at $5,985 per license.
4
ReadyAPI
Answrs VerdictThe enterprise-grade API test suite.
Price: ReadyAPI Test Essentials starts at $5,985 per license billed annually; Test Advanced is custom pricingAdd-ons: VirtServer is from $3,090 and TestEngine is from $4,739AI: Generates tests in plain language, speeding up API testing by up to 80%, and offers an MCP server for Claude, Copilot or terminal agentsProtocols: Tests REST, SOAP, GraphQL, gRPC, Kafka and JMS APIsSecurity: Runs SQL injection, fuzzing and XSS scans as part of automated test runs
ReadyAPI generates tests in plain language, speeding up API testing by up to 80%, and offers an MCP server for Claude, Copilot or terminal agents. It tests REST, SOAP, GraphQL, gRPC, Kafka and JMS and runs SQL injection, fuzzing and XSS scans. Test Essentials starts at $5,985 per license billed annually.
Go ifEnterprise QA teams that need functional, security and load tests with service virtualization
Skip ifYou need a low-cost or free plan
Why #4 over #5: It adds security scans and virtualization that Katalon’s listing does not highlight for APIs.
5
Katalon Studio
Answrs VerdictThe best for API plus UI test automation.
Price: Professional is listed at $2,199 per seat/year, billed annually; a Free plan runs tests locallyAI: AI agents for test automation with low-code authoring, failure analysis and self-healing, plus an MCP serverCoverage: Web, mobile, API and desktop testing in one toolAPI testing: Streamlines testing for any API architecture and unifies API, web and mobile testing in one platformTrial: Enterprise is custom pricing; a 30-day free trial is offered
Katalon Studio uses AI agents for low-code authoring, failure analysis and self-healing, plus an MCP server, across web, mobile, API and desktop tests. Professional is listed at $2,199 per seat/year, billed annually, and a Free plan runs tests locally.
Go ifQA teams that test APIs alongside web and mobile apps in one tool
Skip ifYou only test APIs and want a lightweight client
Why #5 over #6: It tests web, mobile and desktop as well as APIs, which Hoppscotch does not.
6
Hoppscotch
Answrs VerdictThe best free, self-hostable client.
Price: Free $0 forever; Business $6 and Enterprise $11 per user/month billed annuallyTesting: REST, GraphQL and realtime API testing with pre-request scripts, tests, collections and a collection runnerAI and MCP: Business adds MCP server support; Enterprise adds AI Agent featuresOpen source: Self-host from GitHub, with 81k GitHub stars shown on its siteAI Assistant: An agentic chat that edits request fields, runs and saves requests and manages collections and environments; Enterprise Cloud and Enterprise Self-Host only
Hoppscotch is an open-source client for REST, GraphQL and realtime API testing with pre-request scripts, tests and a collection runner. Free is $0 forever, Business is $6 and Enterprise is $11 per user/month billed annually, and you can self-host from GitHub. Business adds MCP server support, and its Enterprise AI Assistant is an agentic chat that edits request fields, runs and saves requests and manages collections and environments.
Go ifDevelopers who want a fast, open-source client they can self-host
Skip ifYou need the AI Assistant without an Enterprise plan
Why #6 over #7: It is free to self-host, while ReadyAPI Test Essentials starts at $5,985 per license.
7
Bruno
Answrs VerdictThe Git-native open-source client.
Price: Open Source $0; Pro $6 and Ultimate $11 per user/month billed annuallyProtocols: HTTP, REST, GraphQL and gRPC in the API clientTesting: Unlimited Collection Runner on every planGit: Native Git integration, with Pro and Ultimate adding Git UI actions such as push and branch checkoutBruno AI: From v4.0.0 with a provider configured: an AI Assistant chat sidebar, inline autocomplete in script editors, and Generate Script, Generate Tests and Generate Documentation
Bruno is an API client for HTTP, REST, GraphQL and gRPC with native Git integration and an unlimited Collection Runner. Open Source is $0, Pro is $6 and Ultimate is $11 per user/month billed annually, and Bruno AI (from v4.0.0, with a provider configured) adds an AI Assistant chat sidebar, inline autocomplete, and Generate Script, Generate Tests and Generate Documentation.
Go ifTeams that keep API collections in Git alongside code
Skip ifYou do not want to configure your own AI provider
Why #7 over #8: Its $6 Pro plan is below Apidog’s $9 Basic.
8
Insomnia
Answrs VerdictThe Kong-backed client with MCP testing.
Price: Essentials is $0; paid plan prices and billing options are on Kong’s Insomnia pricing pageTesting: Unlimited collection runs with pre- and post-request scripting, and the Inso CLI for CI/CD automationAI and MCP: Tests MCP servers with a native MCP client and adds AI-powered workflowsMocking: Native API mocking, with 1,000 mock requests a month included on EssentialsGit: Git Sync for up to 3 users on the free tier
Insomnia runs unlimited collection runs with pre- and post-request scripting, offers the Inso CLI for CI/CD, and tests MCP servers with a native MCP client. Essentials is $0, and paid plan prices and billing options are on Kong’s Insomnia pricing page.
Go ifTeams already on Kong that want API design, mocking and testing together
Skip ifYou want a flat price with no per-user billing
Why #8 over #9: It has a native MCP client, which Schemathesis does not.
9
Parasoft SOAtest
Answrs VerdictThe broadest protocol coverage.
Price: Not published; the product page offers trials and demosAI Assistant: Generates tests, creates data and parameterizes test cases from natural language conversationsProtocols: Supports over 120 message formats and protocols, including MCP-based systems, Kafka and RabbitMQAgentic: MCP server capabilities and agent skills support agentic testing workflows and GitHub Copilot integrationPerformance: Turns functional tests into scriptless protocol-based performance tests
Parasoft SOAtest’s AI Assistant generates tests, creates data and parameterizes test cases from natural language conversations. It supports over 120 message formats and protocols, including MCP-based systems, Kafka and RabbitMQ, and turns functional tests into scriptless performance tests. Pricing is not published.
Go ifRegulated enterprises that need codeless API testing across many protocols
Skip ifYou want a posted price
Why #9 over #10: It supports over 120 protocols, far more than a schema-only fuzzer.
10
Schemathesis
Answrs VerdictThe free schema-driven fuzzer.
Price: Free; open source under the MIT licenseGeneration: Generates test cases from OpenAPI and GraphQL schemas with property-based testingStateful: Chains operations into multi-step workflows inferred from your schemaFuzzing: Fuzz dictionaries mix real IDs, wordlists or LLM-generated payloads with generated dataReports: Exports JUnit, VCR, HAR, NDJSON, JSON or Allure and saves each failure with a curl command
Schemathesis is a free, MIT-licensed tool that generates test cases from OpenAPI and GraphQL schemas using property-based and stateful testing. Fuzz dictionaries can mix LLM-generated payloads with generated data, and each failure is saved with a curl command you can replay.
Go ifDevelopers who want free schema-driven fuzzing in CI
Skip ifYou want a graphical client
How we ranked these
We ranked each tool on how much AI-assisted API test generation, automation and protocol coverage its own pages state, then on published price. The price chart shows only cheapest paid plans with a confirmed annual-billing per-user price; Keploy, Insomnia and Katalon are left out because their billing basis or price is promotional or unconfirmed, and ReadyAPI and Parasoft SOAtest are per-license or quote-only. Where no price is published, we say so. Facts are taken from each maker's own published information; check the official site before you buy.
Questions people ask
What is the best AI tool for API testing?
Postman: it combines the API Client, Collection Runner, monitors and an AI unit test generator, with Solo at $9/mo billed annually.
Which API testing tool is cheapest?
Hoppscotch Business and Bruno Pro are both $6 per user/month billed annually, and both have free plans.
Is there a free open-source API testing tool?
Yes: Schemathesis is MIT-licensed, Keploy’s core is Apache 2.0, and Hoppscotch and Bruno have free plans.
Which tools do not publish a price?
Parasoft SOAtest does not publish a price; ReadyAPI Test Advanced and Katalon Enterprise use custom pricing.
Cheapest paid plan, USD per user per month, billed annually (vendor pricing pages, Oct 2026) at a glance
Hoppscotch6 USD
Bruno6 USD
Postman9 USD
Apidog9 USD
Cheapest paid plan, USD per user per month, billed annually (vendor pricing pages, Oct 2026), as published by each maker. Picks without a published figure are left off.
