Retell AI vs Synthflow:Which is more popular?
In September 2026, Retell AI had more branded searches than Synthflow among AI voice agents worldwide. Retell AI had about 60,500 branded searches, while Synthflow had 4,400. Retell AI made up 49.8% of all AI voice agent searches we track, and Synthflow accounted for 3.6%. When we asked ChatGPT and Google AI Overviews about AI voice agents, Retell AI appeared in all five answers and Synthflow in four. Retell AI was mentioned before Synthflow in every answer.
Who do people search for more?
Retell AI, about 14 searches for every 1 for Synthflow
Who does AI mention more?
Retell AI, mentioned in every answer we collected
Who does AI recommend more?
Retell AI, named ahead of Synthflow in every answer
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Top AI voice agents in ChatGPT and Google AI Overviews
In three ChatGPT questions and two Google AI Overviews, Retell AI appeared in all five answers. Synthflow was mentioned in four out of five: in two of the three ChatGPT answers and in both Google AI Overviews. Retell AI was listed before Synthflow in every answer.
Most recommended by AI
Brands get a higher ranking if they are mentioned earlier in the answers.
Mentioned by AI
Each dot is one answer, filled in when that answer mentions the brand.
- Retell AI5 of 5Named in 3 of 3 ChatGPT answersNamed in 2 of 2 Google answers
Bland AI5 of 5Named in 3 of 3 ChatGPT answersNamed in 2 of 2 Google answers
Vapi4 of 5Named in 3 of 3 ChatGPT answersNamed in 1 of 2 Google answers
Synthflow4 of 5Named in 2 of 3 ChatGPT answersNamed in 2 of 2 Google answers
Voiceflow2 of 5Named in 1 of 3 ChatGPT answersNamed in 1 of 2 Google answers
Air AI0 of 5Named in 0 of 3 ChatGPT answersNamed in 0 of 2 Google answers
Thoughtly0 of 5Named in 0 of 3 ChatGPT answersNamed in 0 of 2 Google answers
See every answer about AI voice agents
5 answers
Asked ChatGPT
“Which AI voice agent platform should I use?”
Asked ChatGPT
“What are the best AI voice agent platforms?”
Asked ChatGPT
“What's the best AI voice agent platform for customer calls?”
Searched Google, AI Overview
“ai voice agent platforms”
Searched Google, AI Overview
“ai phone agent”
Brands are shown in the order each answer named them. The survey took place in the United States on October 20, 2026.
Is Retell AI or Synthflow more popular in search?
This chart shows how often people search Google for Retell AI and Synthflow by name. Each line represents a brand's share of searches for all seven AI voice agents we track, month by month, from English-language searches worldwide.
Share of searches by month for Retell AI, Synthflow. The figures are in the table below the chart.
View monthly share of searches table
| Month | Retell AI | Vapi | Voiceflow | Bland AI | Synthflow | Air AI | Thoughtly |
|---|---|---|---|---|---|---|---|
| Oct 2025 | 37.8% | 16.9% | 25.3% | 8.1% | 7.6% | 2.8% | 1.5% |
| Nov 2025 | 38.9% | 17.4% | 26% | 8.2% | 6.4% | 1.9% | 1.2% |
| Dec 2025 | 43.3% | 15.9% | 23.7% | 7.5% | 5.8% | 2.6% | 1.1% |
| Jan 2026 | 44.7% | 16.4% | 20% | 9.6% | 6% | 2.2% | 1.1% |
| Feb 2026 | 44.5% | 16.3% | 19.9% | 11.3% | 4.9% | 2.2% | 0.96% |
| Mar 2026 | 42.3% | 18.9% | 18.9% | 10.8% | 5.7% | 2.5% | 0.91% |
| Apr 2026 | 43.6% | 19.5% | 19.5% | 9.1% | 4.8% | 2.6% | 0.94% |
| May 2026 | 43.5% | 23.8% | 15.9% | 9% | 4.8% | 2.1% | 0.94% |
| Jun 2026 | 42.4% | 19% | 19% | 10.8% | 4.6% | 3.1% | 1.1% |
| Jul 2026 | 44.2% | 19.8% | 16.2% | 11.2% | 4.8% | 2.6% | 1.2% |
| Aug 2026 | 52.6% | 15.8% | 15.8% | 8.9% | 3.8% | 2.1% | 0.92% |
| Sep 2026 | 49.8% | 14.9% | 14.9% | 12.8% | 3.6% | 3% | 1.1% |
How has the Retell AI and Synthflow comparison changed over the last 12 months?
3 findings
- Retell AI was ahead of Synthflow in every measured month of the 12 months ending September 2026.
- Across the 12 months ending September 2026, Retell AI’s share of searches among AI voice agents worldwide moved from 37.8% to 49.8%, and its estimated monthly branded searches held steady at 60.5K.
- Across the 12 months ending September 2026, Synthflow’s share of searches among AI voice agents worldwide moved from 7.6% to 3.6%, and its estimated monthly branded searches moved from 12.1K to 4.4K.
How did search popularity change for AI voice agents worldwide in September 2026?
2 changes
In September 2026, Retell AI lost share of searches among AI voice agents worldwide, from 52.6% to 49.8%.
Estimated monthly branded searches for Synthflow worldwide fell 63.6% over 12 measured months, from 12.1K to 4.4K in September 2026.
How are branded searches counted?
2 search terms
Brandwave collects information about searches that people make online using Retell AI’s and Synthflow’s names. When viewed over time, estimated search volumes for these branded terms can be used to understand whether interest in the brands is growing, holding steady, or fading.
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