Best API development tools, according to AI.

The top API development tools widely used today include Postman, Apidog, Insomnia, SwaggerHub, Hoppscotch, and Bruno, with each catering to different needs from team collaboration to lightweight testing or Git-based workflows.

Top All-Around API Platforms

Postman: Ideal for teams needing an all-in-one API lifecycle platform, Postman supports designing, mocking, documenting, testing, and monitoring APIs. It has extensive collaboration features, Git integration, mock servers, and automated testing through its collection runner. Postman is popular in enterprise and mid-sized teams and offers free and paid plans starting at $9/user/month Geekflare+1.

Apidog: A newer, unified API platform that treats design as the source of truth. Apidog integrates design, testing, mocking, and documentation in one workspace, reducing toolchain complexity and spec-reality gaps. Free plans exist for small teams, with paid plans from $9/user/month Apidog+1.

Insomnia: Now part of Kong, Insomnia provides clean design-to-test workflows supporting REST, GraphQL, gRPC, and SOAP. It's especially useful for teams using Kong’s API gateway. Offers free and paid tiers from $12/user/month, featuring Git sync and advanced collaboration Geekflare+1.

SwaggerHub: Best for teams working with OpenAPI specifications, providing versioning, team collaboration, and interactive documentation via Swagger UI. Suitable for enterprise teams standardizing API contracts, although testing requires supplementing with other tools. Team plans start around $75/month Apidog.

Lightweight or Developer-Focused Tools

Hoppscotch: Browser-based, open-source API client great for quick testing of REST, GraphQL, MQTT, or WebSocket APIs. No account is required, PWA installable, and free to use, making it ideal for individual developers or small teams Geekflare+1.

Bruno: Git-native, open-source, local-first approach to API testing. Collections are stored as plain text inside your repository, perfect for teams prioritizing version control and code-review workflows. Free with optional paid features Geekflare+1.

HTTPie Desktop and CLI: Command-line testing tools with human-friendly syntax, color-coded JSON output, persistent sessions, and optional desktop clients. Good for debugging APIs in terminals quickly DEV Community.

Thunder Client & REST Client (VS Code Extensions): Lightweight clients integrated directly into VS Code for quick, code-first API testing. Useful for developers who spend most of their time inside the IDE DEV Community.

Specialized Tools

SoapUI / ReadyAPI: Strong for organizations needing SOAP and REST protocol support, including load testing and enterprise-grade testing features. Open-source SoapUI is free; ReadyAPI is licensed for teams Geekflare+1.

LoadView: Cloud-based API load/stress testing, simulating realistic traffic for validating performance under heavy loads, starting at $129/month Geekflare.

Mabl: Combines UI and API test automation for QA teams needing integrated testing workflows. Low-code platform, typically used in enterprise QA contexts Geekflare.

Choosing the Right Tool

For beginners or lightweight use: Hoppscotch, HTTPie, Thunder Client, REST Client. For team collaboration and full lifecycle management: Postman, Apidog, Insomnia, SwaggerHub. For privacy/Git-based workflows: Bruno. For enterprise or complex workflows: Postman Enterprise, SwaggerHub, ReadyAPI, LoadView.

Most tools offer free tiers or trials, which allows trying multiple options and selecting the best fit based on team size, workflow, budget, and API complexity Geekflare+2.

Best API Development Tools (2026)

Here's a breakdown by category, based on what's actually gaining traction with development teams right now:

🏆 API Clients / Testing (Most Widely Used)

Postman remains the default choice for most teams. Postman remains the most widely used API client, but its Team plan now costs $19 per user per month, which has pushed many small teams toward free alternatives. It's praised for being one of the most versatile and widely used API software development and testing platforms that has grown in popularity because of its intuitive user interface and wide range of features, and provides numerous features for API documentation, monitoring, testing, and collaboration.

Free/Open-Source Alternatives — increasingly popular as teams push back on Postman's pricing:

• Bruno and Hoppscotch: both fully free, open-source, and actively maintained, making them the strongest free options in 2026. Bruno specifically stands out for developers who like Git-based workflows — it works well with Git workflows, making version control easy.
• Insomnia: became fully open source again in 2023 after Kong reopened its repository under an Apache 2.0 license. It's known for being user-friendly with a clean design.
• Apidog: becoming popular for its strong capabilities and user-friendly design as an easier Postman alternative.

🎨 API Design & Documentation

SwaggerHub: continues to be a top platform for building API governance and design, based on the OpenAPI Specification (OAS), which is now the industry standard for documentation related to REST APIs, offering an effective ecosystem for API design, documentation, and testing.

Stoplight is also frequently cited alongside Postman as a leading design-first platform for teams building and testing APIs at scale.

🚪 API Management / Gateways (Production)

For running APIs in production, the go-to names are Kong, Tyk, Apigee (Google), AWS API Gateway, and Azure API Management — established enterprise players. A newer entrant worth noting is Zuplo, which differentiates itself with a fully managed, edge-native API management tool that deploys across 300+ global data centers with sub-20-second GitOps deploys, using TypeScript programmable policies instead of XML, Lua, or Go plugins.

🤖 AI-Powered Testing (Emerging)

If you want cutting-edge automation, Keploy is worth a look: it's an open-source platform that automatically records live application traffic and turns those recordings into reusable unit, integration, and API tests, with dependency mocks included.

---

My Practical Recommendation

Most real-world teams don't rely on just one tool — most teams end up using two or three tools from this list together, not one. A common, battle-tested stack looks like:

1. Postman or Bruno — for day-to-day API testing/collaboration
2. SwaggerHub or Stoplight — for API design/documentation
3. Kong or Zuplo — for API gateway/management in production

If budget is a concern for a small team or solo dev, Bruno + Hoppscotch give you nearly all of Postman's core functionality for free. If you're an enterprise needing governance and SSO, Postman's paid tier or SwaggerHub are safer bets.

There’s no single “best” API tool—it depends on whether you’re designing, testing, documenting, mocking, or managing APIs. But these are the most widely used, proven options by real developers and teams.

🧪 API Testing & Development

Postman

• The industry standard for API development & testing.
• Huge feature set: collections, environments, automated tests, mock servers, documentation, monitors.
• Great collaboration features.
• Free tier is solid; paid plans for teams.

Insomnia

• Clean, lightweight alternative to Postman.
• Excellent GraphQL support.
• Built-in design mode with OpenAPI.
• Open-source and free (with paid cloud sync).

Bruno

• The new favorite for Git-friendly API clients.
• Stores requests as plain text files—perfect for version control.
• Offline-first, no account required.
• Great for teams that want “API-as-code.”

Hoppscotch

• Open-source, browser-based, lightning fast.
• Great for quick ad-hoc testing.
• Self-hostable.

🏗️ API Design & Documentation

Swagger / OpenAPI Tools (SmartBear)

• The de facto standard for API specs.
• Swagger Editor, Swagger UI, Swagger Codegen.
• Generate docs and client SDKs from OpenAPI specs.

Stoplight

• Modern, visual API design platform.
• Combines OpenAPI, JSON Schema, and Markdown.
• Excellent for designing and documenting APIs collaboratively.

SwaggerHub

• Team-based API design and publishing.
• Built on OpenAPI; integrates well with CI/CD.

ReadMe

• Very popular for beautiful, interactive API documentation.
• Great developer experience (tutorials, live examples, API keys).
• Used by Stripe, Twilio, etc.

🔧 API Mocking & Virtualization

Prism (by Stoplight)

• Open-source mock server from OpenAPI definitions.
• Great for contract testing and mocking.

Mockoon

• Free, open-source desktop app for creating mock APIs.
• Super easy to set up, no code required.

Postman Mock Server

• Built into Postman—no extra tool needed.

📦 API Gateway & Management

Kong Gateway

• Leading open-source API gateway.
• Lightweight, plugin-rich (auth, rate limiting, logging).
• Used heavily in Kubernetes/cloud-native stacks.

Apigee (Google Cloud)

• Enterprise-grade API management platform.
• Full lifecycle: design, secure, publish, analyze, monetize.
• Used by large enterprises.

AWS API Gateway

• The natural choice if you’re on AWS.
• Serverless-friendly, handles traffic, auth, throttling.
• Pairs with Lambda and CloudFront.

Traefik / NGINX

• Often used as lightweight API gateways/reverse proxies.
• Great for smaller setups or edge routing.

📊 API Monitoring & Analytics

Runscope (by Akamai)

• API monitoring and testing from the cloud.
• Alerting, validation, scheduled tests.

UptimeRobot / Better Uptime

• Simple uptime/API endpoint monitoring.
• Good for basic health checks.

Datadog API Monitoring

• Full observability if you already use Datadog.
• Tracks latency, errors, and traffic.

🧪 Load & Performance Testing

JMeter (Apache)

• Open-source, battle-tested.
• Heavyweight but powerful for load testing APIs.

k6 (Grafana)

• Modern, scriptable load testing tool.
• Uses JavaScript; great with CI/CD.

Artillery

• Easy-to-use Node.js load testing tool.
• YAML-driven, good for API and socket tests.

---

TL;DR – Most Popular by Category

For most daily API development work, Postman + OpenAPI/Swagger covers 90% of needs. If you prefer a modern, Git-centric workflow, try Bruno + Stoplight.

The API development landscape has experienced a massive shift. While legacy tools still hold a significant market share, developer preferences have pivoted heavily toward local-first, Git-friendly, and open-source workflows, largely driven by changes in licensing, pricing, and cloud-syncing requirements of major vendors.

The best API development tools are categorized below by their primary function in the API lifecycle, highlighting the industry standards developers actually use.

---

1. API Clients & Testing Workspaces (The Core Sandbox)

This is where developers write, test, and debug API requests.

Bruno (The Breakout Star)

• What it is: A fast, lightweight, open-source, and entirely offline-first API client.
• Why people love it: Instead of locking your API collections in a proprietary cloud database, Bruno saves them as plain text files (.bru) directly in your project folder. This means you can use your normal Git workflows (commits, branches, pull requests) to collaborate on APIs.
• Best for: Developers who want privacy, offline capabilities, and painless Git collaboration without a forced cloud login.

Apidog (The Ultimate Postman Alternative)

• What it is: An integrated platform that combines API design, debugging, automated testing, and documentation.
• Why people love it: Apidog bridges the gap between raw API clients and complex lifecycle managers. It has risen drastically in popularity as a replacement for Postman. It offers an "API Design-first" approach where your documentation, tests, and mock servers automatically sync whenever you update your API spec.
• Best for: Teams looking for a free or highly affordable collaborative workspace that handles everything from design to automated testing in one UI.

Postman (The Enterprise Giant)

• What it is: The most feature-rich, widely used, and established API platform in the world.
• Why people use it: It has the most extensive ecosystem, robust enterprise features, public API networks, and excellent built-in automated testing with JavaScript.
• The Catch: Postman has faced significant developer backlash for pushing heavily toward a cloud-first architecture, forcing accounts, and restricting its free plan. It remains the corporate enterprise standard but is increasingly bypassed by individual developers and startups.

Insomnia (The Multi-Protocol Specialist)

• What it is: A sleek, beautiful API client owned by Kong.
• Why people love it: It supports REST, GraphQL, gRPC, and WebSockets natively with an incredibly clean UI. It sits as a middle-ground option, offering flexibility between local, Git, or cloud storage.
• Best for: Teams dealing heavily with mixed protocols (like GraphQL and gRPC alongside REST).

---

2. API Mocking & Interception (For Frontend & QA Testing)

These tools allow you to simulate APIs before they are built, or intercept traffic to test edge cases.

Mockoon

• What it is: The easiest, open-source tool to design and run mock APIs locally.
• Why people love it: There is no registration required. Within seconds, you can spin up a local mock server, define custom responses, add latency, and simulate server errors. It is highly valued for frontend developers who need to code against a backend that doesn't exist yet.

Requestly

• What it is: A local-first developer tool that allows you to intercept and modify HTTP/HTTPS requests.
• Why people love it: It allows you to intercept API calls on live websites and redirect them to your local environment, mock responses, or inject headers. It’s an essential tool for debugging production bugs locally.

---

3. API Design & Documentation (Defining the Contract)

When building production APIs, defining a clear contract (schema) is critical for front-end and back-end alignment.

Swagger / OpenAPI Initiative

• What it is: The undisputed global standard framework for describing and designing RESTful APIs.
• Why people use it: Virtually every major framework can automatically generate Swagger (OpenAPI) specifications from code (and vice-versa). Tools like Swagger Editor and Swagger UI are the industry-default ways to visualize API endpoints.

Redocly

• What it is: A documentation engine that takes your OpenAPI/Swagger YAML files and turns them into gorgeous, searchable, and interactive developer portals.
• Why people love it: It creates incredibly polished, clean documentation layouts (similar to Stripe’s highly praised docs) and handles large-scale API definitions with ease.

---

4. API Gateways & Management (Production & Security)

Once APIs are built, these tools handle routing, security, rate limiting, and analytics in production.

Kong Gateway

• What it is: The most popular open-source, cloud-native API gateway.
• Why people use it: Built on top of Nginx, Kong is incredibly fast and lightweight. It acts as the "front door" for microservice architectures, handling authentication, rate-limiting, and logging via a robust ecosystem of plugins.

Apigee (by Google Cloud)

• What it is: An enterprise-grade API management platform.
• Why people use it: Apigee is the heavy-duty standard for massive organizations. It is unmatched in its security, hybrid/multi-cloud deployment options, developer portal hosting, and monetization analytics, though it comes with enterprise-level pricing.

---

Which tool should you choose?

• If you are a privacy-conscious developer or Git-centric team, use Bruno.
• If you want a unified, modern, and cheap collaboration platform for the whole API lifecycle, use Apidog.
• If your company is a large enterprise with deep integrations and legacy setups, stick to Postman.
• If you need to simulate backend APIs locally, use Mockoon.

The best API development tools vary depending on whether you are designing, testing, or managing APIs.

Top API Development Tools

Postman: This is the most popular industry-standard platform for building, testing, and designing APIs. Best For: Collaborative API design, comprehensive automated testing, and mock servers. Key Features: Comprehensive environment variables, extensive request chaining, and built-in API documentation generators. Insomnia: This is a streamlined, developer-focused alternative to Postman that prioritizes speed and simplicity. Best For: Quick ad-hoc testing and lightweight GraphQL or REST requests. Key Features: Clean user interface, robust environment management, and native Git integration for version control. Swagger / OpenAPI: This is the definitive framework for describing, producing, and consuming RESTful web services. Best For: Designing API architecture before writing code (API-first development). Key Features: Interactive documentation generation, auto-generated client SDKs, and strict schema validation. Hoppscotch: This is a free, fast, and beautiful open-source API request builder. Best For: Developers who want a lightweight web-based alternative to heavy desktop applications. Key Features: Web-native architecture, full WebSocket support, and real-time collaborative spaces. Bruno: This is a fast-growing, open-source desktop app that rethinks how API collections are stored. Best For: Teams that want to save API collections safely in Git repositories. Key Features: Plain-text markup storage format, offline-first design, and zero cloud-sync data privacy issues.

Choosing the Right Tool

Choose Postman if your enterprise team needs central collaboration and advanced automated testing. Choose Bruno or Insomnia if you prefer a fast desktop app that handles plain-text files easily. Choose Hoppscotch if you want an open-source, web-based tool without downloading software.

To help narrow down the list, tell me:

What programming languages or frameworks are you using? Do you need features like automated CI/CD testing or team collaboration? Are you working primarily with REST, GraphQL, or gRPC APIs?

Postman is the dominant choice for most developers and teams working on API development, testing, documentation, and collaboration. It supports the full API lifecycle (request building, collections, automated testing, mocking, monitoring, and team workspaces) and is frequently described as the industry standard or default tool that developers learn first.

It appears at or near the top of nearly every 2025–2026 roundup, G2 leaderboards, StackShare popularity lists, and market analyses, with massive adoption (tens of millions of users and high Fortune 500 penetration). Drawbacks include pricing on team plans (which has driven some migration) and past friction around mandatory accounts. The free tier still works well for individuals or small teams.

Strong open-source or lightweight alternatives to Postman (often recommended when teams seek lower cost, simplicity, or Git-native workflows) include:

• Insomnia — Clean, fast UI with excellent REST/GraphQL/gRPC support, scripting, environments, and plugins. It became fully open-source again and is a frequent Postman alternative in reviews.
• Hoppscotch — Browser-based, fully open-source client with high user ratings and an active community; popular for its lightweight feel.
• Bruno — Git-native and open-source, favored for version-controlled testing and modern workflows.

Apidog is an emerging all-in-one platform gaining traction for unified design, testing, mocking, and docs with strong ease-of-use scores.

For API design and documentation (design-first workflows), the OpenAPI/Swagger ecosystem is the de facto standard. Key tools include:

• Swagger Editor and Swagger UI (open-source) — Widely used for creating, validating, and visualizing OpenAPI specs, with auto-generated interactive docs.
• SwaggerHub (SmartBear) — Collaborative platform for design, governance, and docs.

Related options like Redocly (excellent rendering), Stoplight (visual design + governance), and others build on the same OpenAPI foundation.

Other notable mentions:

• Thunder Client or similar VS Code extensions for lightweight, editor-integrated testing.
• HTTPie (CLI tool) for quick command-line work.
• Enterprise/API management platforms like Kong, Apigee, AWS API Gateway, or MuleSoft when the focus extends to gateways, security, or large-scale lifecycle management (these overlap with development but are more runtime-oriented).

Trends and context (as of 2025–2026 data): Postman leads in overall usage and collaboration features, but open-source options (Insomnia, Hoppscotch, Bruno) are rising due to cost and preferences for simplicity or Git integration. OpenAPI remains the universal spec for design/docs. Many teams use a combination (e.g., OpenAPI for specs + Postman or an alternative for testing).

Recommendations depend on needs: Postman for comprehensive team collaboration; open-source alternatives for cost/simplicity; Swagger/OpenAPI tools for spec-driven design. Check current pricing, integrations (e.g., CI/CD), and try free tiers, as the space evolves quickly with AI-assisted features appearing across tools.

Here are the API development tools I’d actually shortlist in 2026, focusing on brands/products that real teams commonly use—not obscure “top 50” list filler.

Quick recommendation

If you want the safest default stack:

1. Postman — best all-around API platform for most teams.
2. OpenAPI + Swagger / Swagger Studio — best for API design, specs, docs, and codegen workflows.
3. Insomnia — best lightweight Postman-style client.
4. Bruno — best Git-friendly, offline-first API client.
5. Hoppscotch — best open-source / self-hostable API client platform.
6. Apidog — best all-in-one Postman alternative for design, mock, test, docs.
7. ReadyAPI / SoapUI — best enterprise QA/API testing, especially if you have SOAP or heavy test automation.
8. Pact — best for consumer-driven contract testing in microservices.
9. Mockoon or WireMock — best for API mocking and service virtualization.
10. Kong, Apigee, AWS API Gateway, Azure API Management — best for API gateways and production API management.

---

Best API development tools by use case

---

My practical picks

1. Postman — best default for most teams

Choose Postman if you want one tool that almost everyone knows. It is strong for manual API calls, collections, environments, pre-request scripts, tests, documentation, mock servers, monitors, collaboration, and enterprise governance. It is the safest recommendation if you work with mixed backend, frontend, QA, product, and DevRel teams. (learning.postman.com)

Best for: most startups, internal engineering teams, API consumers, DevRel teams, QA collaboration.

Downside: heavier than lean clients; pricing/cloud/collaboration preferences may push some teams toward Bruno, Insomnia, or Hoppscotch.

---

2. Swagger / OpenAPI — best foundation

Regardless of which client you use, I’d standardize on OpenAPI for REST/HTTP APIs. OpenAPI provides a vendor-neutral JSON/YAML description of an HTTP API, which other tools can use for docs, validation, mocks, tests, SDKs, and governance. (openapis.org)

For tooling, Swagger Studio / SwaggerHub is still one of the most recognizable choices for OpenAPI-first design and documentation. It supports OpenAPI and AsyncAPI, collaboration, hosted definitions, shared components, version management, private/public sharing, and code generation integrations. (support.smartbear.com)

Best for: API-first teams, platform teams, public APIs, SDK generation, documentation-first workflows.

---

3. Insomnia — best lean Postman alternative

Insomnia is a good pick if developers mostly need a fast API client for REST, GraphQL, gRPC, WebSockets, SOAP, and SSE without the full “API platform” feel. (insomnia.rest)

Best for: individual developers, backend teams, GraphQL/gRPC users, teams that find Postman too heavy.

---

4. Bruno — best Git-friendly offline client

Bruno is one of the most compelling newer tools because it is offline-first, open-source, and stores collections directly as files that work naturally with Git. That makes it attractive for teams that want API requests versioned and reviewed like code. (docs.usebruno.com)

Best for: privacy-sensitive teams, Git-based workflows, teams avoiding cloud sync or account requirements.

---

5. Hoppscotch — best open-source/self-hostable option

Hoppscotch is a strong option if you want an open-source API development ecosystem with cloud, self-hosted, desktop, and team features. It supports workspaces, roles, real-time collaboration, collections, environments, pre-request scripts, post-request tests, audit logs, SSO, and on-prem deployment. (hoppscotch.com)

Best for: self-hosters, open-source-friendly teams, companies with data-residency concerns.

---

6. Apidog — best all-in-one alternative

Apidog is worth considering if you want one tool for API design, debugging, mocking, testing, documentation, and team collaboration. It also emphasizes spec-driven workflows, automatic mock data, response validation, visual assertions, request sequences, Postman-script compatibility, and self-hosted runners. (docs.apidog.com)

Best for: teams that want Postman + Swagger + mock server + docs in one integrated product.

---

7. ReadyAPI / SoapUI — best enterprise testing

If your organization has formal QA, regulated environments, legacy SOAP services, or large regression suites, ReadyAPI / SoapUI is still a serious option. It is less “developer casual” than Postman or Bruno, but stronger for enterprise-grade API testing programs. (smartbear.com)

Best for: QA teams, enterprise test automation, SOAP-heavy environments, compliance-sensitive teams.

---

8. Pact — best contract testing

Use Pact when teams independently own microservices and you need confidence that consumers and providers won’t break each other. Pact focuses on consumer-driven contracts, where API consumers define expectations and providers verify against them. (docs.pact.io)

Best for: microservices, distributed teams, CI/CD quality gates, avoiding integration failures.

---

9. Mockoon / WireMock — best mocking

Use Mockoon for quick local mock REST APIs with no account and no remote deployment. Use WireMock when you need more advanced service virtualization: request matching, templating, latency/fault injection, record/playback, and dependency simulation. (mockoon.com)

Best for: frontend-backend parallel development, third-party API dependency simulation, integration testing.

---

10. Kong / Apigee / AWS API Gateway / Azure API Management — best production API management

These are not primarily “send a request from my laptop” tools. They are for production API management: gateways, auth, rate limiting, policies, developer portals, analytics, security, scaling, and governance. Kong is popular for cloud-native gateway use cases; Apigee is a mature enterprise API management platform; AWS API Gateway and Azure API Management are natural choices if you are deep in those clouds. (developer.konghq.com)

---

What I’d choose

• Solo developer: Postman or Bruno.
• Small dev team: Postman if collaboration matters; Bruno if Git/local-first matters.
• Open-source/self-hosted team: Hoppscotch or Bruno.
• API-first product team: OpenAPI + Swagger Studio or Redocly + Postman/Bruno.
• QA-heavy enterprise: ReadyAPI + Postman + Pact.
• Microservices org: OpenAPI + Pact + Postman/Bruno + Kong/Apigee/Azure/AWS gateway.
• Frontend team waiting on backend: Mockoon or WireMock.

My default recommendation: start with Postman + OpenAPI/Swagger. If your team dislikes Postman’s weight or cloud orientation, switch the daily client to Bruno or Insomnia, but keep OpenAPI as the source of truth.

The most widely used API development tools are Postman, Swagger/OpenAPI tools (especially SwaggerHub and Swagger UI/Editor), Insomnia, Apidog, SoapUI, and HTTPie. For enterprise API management, Apigee, Gravitee.io, Kong, and AWS API Gateway are the names that show up repeatedly in current lists and category rankings.

If you want the best products people actually use, I’d narrow it to this shortlist:

• Postman — best all-around choice for API design, testing, documentation, and team collaboration; it is repeatedly described as the most widely used and a category leader.
• Swagger/OpenAPI (SwaggerHub, Swagger UI, Swagger Editor) — best for OpenAPI-first design and documentation, especially when specs drive the workflow.
• Insomnia — strong for API testing and client workflows, often recommended alongside Postman for teams.
• Apidog — increasingly popular all-in-one platform for design, mock, test, and collaboration; G2 highlights it as easiest to use in enterprise API development.
• SoapUI — a long-standing choice for deeper SOAP and REST functional testing.
• HTTPie — preferred for a lightweight, terminal-first API client and scripting workflows.
• Bruno — good for teams that want API tests to live in Git and follow code review workflows.
• Apigee — a top enterprise API management platform for governance, security, and lifecycle management.
• Gravitee.io — a notable enterprise competitor and current G2 trending leader in API development.
• Kong — commonly cited for API gateway and management use cases.

A practical way to choose is:

If you want a single recommendation, Postman is the safest default because it is consistently ranked as the leader and is repeatedly described as the most widely used API tool for testing, documentation, and collaboration. If you want an OpenAPI-first stack, choose Swagger/OpenAPI tools; if you need enterprise governance, choose Apigee or Gravitee.io.