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Alternatives

Products that do what Whirlsen does

Developer-Focused Interface

  1. 1IR

    Sharing an internal tool that accelerated my development work 10-fold, especially with API debugging. Thought fellow developers here might find it useful. As a developer, I often have trouble reproducing errors at the client end. https://intercept.rest lets me debug and monitor API requests and responses. It is similar to the Network tab in Chrome Developer Tools but works for any API: mobile apps, webhooks, frontend etc. After I shared it with a close circle of friends, they found it incredibly useful and even found new use cases, I never imagined. Been a long time lurker here and…

    2018

  2. 2

    A HTTP-based API simulator to assist parallel development 🛠️

    2018

  3. 3

    Website load testing made easy

    2021

  4. 4
    Decoy99

    Local server mocks in macOS, all in a lightweight native app

    Mar 2026

  5. 5

    Maximize conversions with no-code A/B testing and analytics

    2024

  6. 6
    AbTest.io122

    A free url shortener with A/B testing features

    2017

  7. 7

    Link your app design to API calls

    2022

  8. 8MM
  9. 9

    Build relevant search with NoCode, JS components or REST API

    2020

  10. 10
    RAGaaS75

    The API for building production-ready AI apps with your data

    2025

  11. 11
    Gremlin81

    Run chaos engineering experiments safely and securely

    2019

  12. 12

    World's most intelligent web app & API security scan tool

    2024

  13. 13
    Loader.io117

    Simple cloud-based load testing for your apps

    2014

  14. 14

    Build, Test & Document APIs in Plain text files with blocks

    Jan 2026

  15. 15

    Free dev tool to collect enriched user feedbacks

    2018

  16. 16OA
  17. 17AS

    2012 · apiaxle.com

  18. 18

    Hi HN, I built the first version of Mocktail years ago. I recently came back to the project, and after a pretty substantial rebuild, v4 is now out. Mocktail is a free and open-source, self-hosted mock API server with a built-in dashboard and database, packaged as a single ~25 MB binary. You can run it locally or on your own infrastructure — no account or hosted service required. You can define endpoints and responses, generate realistic data per request, customize headers, status codes and latency, and inspect incoming requests in real time. With v4, I also added MCP support, so coding…

    22d ago · getmocktail.com

  19. 19

    The Fastest Way to Test API Security Inside Chrome DevTools

    Jul 2026 · webslurp.github.io

  20. 20

    SHARP EYES ON EVERY API

    21d ago · api-spector.dev

  21. 21IV

    Hi HN,<p>In my spare time (evenings and weekends) I've built 3 products which have been relatively successful even with little advertising (only google ads budgeted at $30 per day). The latest one is WcfStorm.Rest; which is a REST service test client. I built it because I found that the current tools did not have the features I wanted such as, intellisense when working with HTTP headers, syntax highlighting for JSON messages, etc.<p>I'm continually trying to improve these products and would very much love get your feedback. Every suggestion is welcome!<p>(My apologies…

    2012 · wcfstorm.com

  22. 22

    Real users, verified app tests, actionable feedback

    Jul 2026

  23. 23WD

    Easily test your webhooks and emails with our straightforward tool.

    2024 · wt.dev

  24. 24GB

    Hey HN, We’re excited to share PySpur, an open-source tool that provides a graph-based interface for building, debugging, and evaluating LLM workflows. Why we built this: Before this, we built several LLM-powered applications that collectively served thousands of users. The biggest challenge we faced was ensuring reliability: making sure the workflows were robust enough to handle edge cases and deliver consistent results. In practice, achieving this reliability meant repeatedly: 1. Breaking down complex goals into simpler steps: Composing prompts, tool calls, parsing steps, and branching…

    2024 · github.com

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