AI Tool Comparison
Relay.app vs Retell AI
A side-by-side breakdown to help you pick the right tool for your workflow.
Relay.app
Turn plain-language descriptions into working automations across hundreds of apps, with human-in-the-loop approval steps built in.
Retell AI
Power phone and chat agents that sound natural in conversation, assembled from any mix of LLM, voice, and telephony provider.
Bottom Line
Last reviewed: August 2026
Relay.app and Retell AI both sit in Automation, but they're built around different use cases within it. Both carry the same 4.5 rating, so the decision comes down to fit, not quality.
Choose Relay.app if…
Best for teams whose workflows genuinely need a human approval or review step, not full automated end-to-end flows, and its edge is builds structured human decision points directly into the automation instead of treating every step as fire-and-forget. The right tool when human judgment matters mid-workflow, it's a newer, smaller product than Make for complex flows.
Choose Retell AI if…
Best for businesses that want phone-based voice agents handling calls at scale without piecing together the voice stack themselves, and its edge is a visual workflow builder handles call logic with no code, on top of a managed speech-to-text-to-LLM-to-speech pipeline. A genuine full-stack shortcut versus building from raw APIs, per-minute costs climb fast at real production volume.
| Attribute | Relay.app | Retell AI |
|---|---|---|
| Category | Automation | Automation |
| Pricing | freemium | freemium |
| Pricing Detail | Free (500 credits) / $19/mo Professional / $59/mo Team | Pay-as-you-go from $0.07-0.31/min / Enterprise custom |
| Rating |
Key Features
Relay.app
- Human approval steps
- AI actions
- Shared workflow visibility
- Template library
- Collaboration tools
Retell AI
- Inbound and outbound calling
- Visual call flow builder
- CRM integrations
- Call recording and transcripts
- Phone number provisioning
- Real-time analytics
Pros
Relay.app
- •Best for workflows requiring human review
- •Transparent and auditable
- •Good team features
- •Clean interface
Retell AI
- •Full-stack voice solution, less infrastructure than building from components
- •Visual workflow builder requires no code for call logic
- •Strong integrations with healthcare and real estate tools
Cons
Relay.app
- Less powerful than Make for complex flows
- Small app library
- Newer product
Retell AI
- Per-minute costs scale quickly at production volume
- Less model flexibility than raw API alternatives