OpenAI Text-to-Speech API
OpenAI's text-to-speech API — converts text to natural speech with 6 built-in voices (Alloy, Echo, Fable, etc.) and streaming support, using the same API key as GPT.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
HTTPS enforced. Same security posture as OpenAI Chat API (SOC 2 Type II). API key management via OpenAI dashboard. Organization-level keys supported. Audio data not retained after processing.
⚡ Reliability
Best When
You're already using OpenAI APIs and need simple, high-quality TTS with minimal setup — same API key, excellent Python SDK, clean integration.
Avoid When
You need custom voice cloning, ultra-low latency, or very high request volumes where per-character costs matter significantly.
Use Cases
- • Adding voice output to ChatGPT-style agent interfaces
- • Converting agent responses to audio for accessibility or voice UI
- • Streaming TTS for real-time voice agent conversations (gpt-4o-realtime)
- • Generating audio for content creation (narration, audiobooks)
- • Multi-modal agent output combining text and speech
Not For
- • Voice cloning or custom voice creation (use ElevenLabs for custom voices)
- • High-fidelity studio-quality audio production
- • Languages beyond the ~57 supported (ElevenLabs has broader language support)
Interface
Authentication
Same API key as all other OpenAI APIs. Optionally scoped to organization. No TTS-specific permissions — key has full API access.
Pricing
Straightforward per-character pricing. TTS-1 is faster and cheaper; TTS-1-HD is higher quality. gpt-4o-audio is separate pricing.
Agent Metadata
Known Gotchas
- ⚠ 4096 character input limit per request — agents must chunk longer texts
- ⚠ Response is raw binary audio — no JSON wrapper; content-type is audio/mpeg
- ⚠ Voice selection is from 6 fixed options — no custom voices unlike ElevenLabs
- ⚠ No word-level timestamps — if you need timing, use Whisper separately
- ⚠ Streaming writes audio chunks incrementally — proper streaming client handling required
Alternatives
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Scores are editorial opinions as of 2026-03-07.