Best AI tools to build AI agents
| Tool | What it does | Pricing | Free tier | Refunds |
|---|---|---|---|---|
| AssemblyAI | Voice AI infrastructure providing speech-to-text, voice agent, and speech understanding APIs for developers. | Free tier | Yes | None stated |
| Zapier | No-code automation platform that connects and moves data between thousands of different web applications and services. | Free tier; paid from $19.99/mo | Yes | — |
| Taskade | AI app builder that turns one prompt into apps, agents, and automated workflows in a living workspace. | Free tier; paid from $10/mo | Yes | — |
| GPT-trainer | Build AI agents with a multi-agent framework, no-code UI, and versatile API for voice and text automation. | Free tier; paid from $150/mo | Yes | None stated |
| Speechmatics | Speech-to-text and text-to-speech technology for developers and enterprise. | Free tier | Yes | — |
— means the vendor does not state it on the pages we read.
AssemblyAI
Visit AssemblyAIassemblyai.com
Voice AI infrastructure providing speech-to-text, voice agent, and speech understanding APIs for developers.
End-to-end voice agent infrastructure, built on our industry-leading Realtime Speech-to-Text API.
Pricing, in their words: “Start free, pay-as-you-go after that – no commitments required.” (pricing)
Subscription terms they state: states no refunds (source)
Limits the vendor states:
- no programmatic extraction
Zapier
Visit Zapierzapier.com
No-code automation platform that connects and moves data between thousands of different web applications and services.
Create your own AI assistants for any task
Pricing, in their words: “Zapier automation platform Unlimited Zap workflows, Tables, and Forms Two-step Zap workflows” (pricing)
Subscription terms they state: cancel in-app · auto-renews (source)
Limits the vendor states:
- No high-risk activities
- No sensitive personal data usage
Taskade
Visit Taskadetaskade.com
AI app builder that turns one prompt into apps, agents, and automated workflows in a living workspace.
Build, train, and deploy agents for any role — support, sales, research, ops, or custom tasks.
Pricing, in their words: “Monthly/YearlySave 50%” (pricing)
Subscription terms they state: auto-renews (source)
Limits the vendor states:
- No professional advice
GPT-trainer
Visit GPT-trainergpt-trainer.com
Build AI agents with a multi-agent framework, no-code UI, and versatile API for voice and text automation.
Build powerful voice and text AI agents. Delivered across phone calls, email, SMS, web chat, and social media.
Pricing, in their words: “Self-Serve $150 USD Billed monthly” (pricing)
Subscription terms they state: states no refunds (source)
Limits the vendor states:
- no refunds
Speechmatics
Visit Speechmaticsspeechmatics.com
Speech-to-text and text-to-speech technology for developers and enterprise.
Whether you need leading real-time speech-to-text or an end-to-end voice agent API, build with the best ears in AI.
Pricing, in their words: “From 1 August 2026, Speechmatics moves to credit-based billing: one credit balance across every product, same prices, no action needed.” (pricing)
Subscription terms they state: auto-renews (source)
Limits the vendor states:
- No reverse engineering
- No standalone resale
FAQ
Is there a free tool to build ai agents?
Yes — AssemblyAI, Zapier, Taskade, GPT-trainer, Speechmatics offer a free tier.
What is the cheapest paid option to build ai agents?
Speechmatics starts at $0/month.
Which of these have an API?
AssemblyAI, Zapier, Taskade, GPT-trainer, Speechmatics document a developer API.
How do I cancel these subscriptions?
Zapier: cancel in-app. AssemblyAI, Taskade, GPT-trainer, Speechmatics do not state a cancellation route on the pages we read.
Can I get a refund?
AssemblyAI states it does not offer refunds; GPT-trainer states it does not offer refunds. The others (Zapier, Taskade, Speechmatics) do not state a refund policy on the pages we read.
Do these subscriptions auto-renew?
Zapier, Taskade, Speechmatics state that paid plans renew automatically. Check the billing page before subscribing; the rest do not state it either way.
Sources
Every fact above was read from the vendors' own pages: