GLM / Z.ai (Zhipu AI) vs Grok Speech (STT + TTS APIs)
Which one should you pick? Here's the full breakdown.
GLM / Z.ai (Zhipu AI)
Zhipu AI's open-weights family -- GLM-5.1 (launched 2026-04-07) is 744B MoE / 40B active, topped SWE-Bench Pro at 58.4 (beating GPT-5.4 and Claude Opus 4.6), MIT licensed, 200K context. Trained entirely on 100K Huawei Ascend 910B chips -- first frontier model with zero Nvidia in the training stack
Grok Speech (STT + TTS APIs)
xAI's standalone voice APIs -- launched 2026-04-17. Built on the stack that powers Grok Voice, Tesla vehicles, and Starlink customer support. $0.10/hr STT batch, $4.20 per 1M characters TTS, 25+ languages, word-level timestamps + speaker diarization
| Category | GLM / Z.ai (Zhipu AI) | Grok Speech (STT + TTS APIs) |
|---|---|---|
| Ease of Use | 6.5 | 7.0 |
| Output Quality | 8.5 | 8.5 |
| Value | 9.0 | 9.0 |
| Features | 8.0 | 8.0 |
| Overall | 8.0 | 8.1 |
Pricing Comparison
| Feature | GLM / Z.ai (Zhipu AI) | Grok Speech (STT + TTS APIs) |
|---|---|---|
| Free Tier | Yes | No |
| Starting Price | $0 | $0.10 |
Benchmark Head-to-Head
GLM-5.1 (744B MoE / 40B active) benchmarks — Grok Speech (STT + TTS APIs) has no published benchmarks
| Benchmark | Description | Score |
|---|---|---|
| SWE-Bench Pro | 58.4% | |
| MMLU-Pro | Harder multi-subject reasoning | 81.2% |
| GPQA Diamond | Graduate-level science questions | 74.5% |
| HumanEval | Python code generation | 89.1% |
| SWE-Bench Verified | 64.2% | |
| BFCL (function calling) | 88% |
Which Should You Pick?
Pick GLM / Z.ai (Zhipu AI) if...
- ✓Has a free tier
Teams that need genuine MIT-licensed frontier open weights with no commercial strings. Especially strong for agentic workflows and vision (GLM-4.6V).
Visit GLM / Z.ai (Zhipu AI)Pick Grok Speech (STT + TTS APIs) if...
Developers building voice agents, real-time transcription tools, accessibility features, or high-volume TTS workloads where the cost per hour of audio actually matters at scale. Strong fit for phone-call and meeting transcription use cases where xAI's published WER advantage (5.0% on phone-call entities vs. ElevenLabs 12.0%) compounds quickly.
Visit Grok Speech (STT + TTS APIs)Our Verdict
GLM / Z.ai (Zhipu AI) and Grok Speech (STT + TTS APIs) are extremely close overall. Your choice comes down to specific needs -- GLM / Z.ai (Zhipu AI) is better for teams that need genuine mit-licensed frontier open weights with no commercial strings, while Grok Speech (STT + TTS APIs) works best for developers building voice agents, real-time transcription tools, accessibility features, or high-volume tts workloads where the cost per hour of audio actually matters at scale.