TTS API comparison 2026
Gradium TTS Beta vs Resemble AI Chatterbox HD Gradium vs Resemble AI · text-to-speech for voice agents
Gradium TTS Beta ranks 1st of 112 with 76.8/100; Resemble AI Chatterbox HD ranks 60th with 7.3/100: a gap of 69.5 points on the same public rules, built on Coval, Speko and Artificial Analysis.
Data checked on September 30, 2026 · Coval 30-day window ending October 1, 2026 · updated after each benchmark capture
Side-by-side benchmark
| Measure | Gradium TTS Beta | Resemble AI Chatterbox HD |
|---|---|---|
| Overall score | 76.8/100 | 7.3/100 |
| Rank | 1st of 112 | 60th of 112 |
| Real-time speed /60 | 58.7 | 0 |
| Voice quality /20 | 7.8 | 6.4 |
| Accuracy /15 | 9.8 | 0 |
| Price /5 | 0.5 | 0.9 |
| P50 / median time-to-first-audio Coval, 30-day window | 47.2 ms | not measured |
| P99 time-to-first-audio (slowest turns) Coval, 30-day window | 108.8 ms | not measured |
| Latency consistency (standard deviation) Coval, 30-day window | 16.6 ms | not measured |
| P50 time-to-first-audio, US East Speko | 100 ms | not measured |
| Accuracy: word error rate (WER) Coval, 30-day window | 4.5% | not measured |
| Pronunciation robustness (0 to 1) Speko | 0.3 | not measured |
| Speech Arena Elo (blind listener preference) Artificial Analysis | not measured | 1101 |
| Naturalness (Elo) Speko | 1579 | not measured |
| Price per 1M characters Artificial Analysis | not measured | 40 USD |
Choose Gradium TTS Beta if…
- → Ranks 1st of 112 in the overall benchmark, against 60th for Resemble AI Chatterbox HD
Choose Resemble AI Chatterbox HD if…
On the published benchmarks, Resemble AI Chatterbox HD wins none of the measurements above against Gradium TTS Beta. This says nothing about features the benchmarks do not measure.
Resemble AI Chatterbox HD: all measurements →Frequently asked questions
- What is the difference between Gradium TTS Beta and Resemble AI Chatterbox HD?
- In the 2026 TTS API benchmark, Gradium TTS Beta ranks 1st of 112 with 76.8/100 and Resemble AI Chatterbox HD ranks 60th with 7.3/100, a gap of 69.5 points on the same rules.
- Which is faster for real-time voice agents, Gradium TTS Beta or Resemble AI Chatterbox HD?
- On Coval's 30-day window ending October 1, 2026, the P50 time-to-first-audio is 47.2 ms for Gradium TTS Beta and not measured for Resemble AI Chatterbox HD; the P99 is 108.8 ms and not measured.
- On which criteria does Resemble AI Chatterbox HD beat Gradium TTS Beta?
- Resemble AI Chatterbox HD scores higher on Price (0.9 vs 0.5 out of 5).
- How are these two text-to-speech APIs scored?
- Both are scored by the same public rules: 4 criteria, 100 points (Real-time speed 60, Voice quality 20, Accuracy 15, Price 5), computed from three independent benchmarks: Coval, Speko and Artificial Analysis. A measurement a benchmark does not publish counts zero, and the model page says why.
- Can these numbers be checked?
- Yes. Each model page lists every measurement with its source and date, and links to the benchmark page it comes from. The rules are on the methodology page.