Amazon Polly production TTS

Use Amazon Polly when the job needs AWS-hosted text-to-speech with predictable API operations, IAM governance, lexicons, SSML, and reusable generated audio. Treat Polly as a production TTS service, not a voice-cloning system: it provides AWS-managed voices and engines, not custom voice training or arbitrary speaker imitation.

Facts below were verified from official AWS documentation on 2026-07-10. Re-check AWS docs before relying on volatile facts such as prices, quotas, regions, voice lists, or engine feature compatibility.

First decision: which operation and engine

Choose the operation first, because it defines latency, output custody, and timing options:

• SynthesizeSpeech: real-time request/response. Use for short narration lines, UI prompts, voice preview, batch segment synthesis, and speech-mark JSON. Input limit is 6,000 total characters, with no more than 3,000 billed characters; output audio is cut off after 10 minutes. Documented fact: https://docs.aws.amazon.com/polly/latest/dg/limits.html
• StartSpeechSynthesisTask: asynchronous synthesis to Amazon S3, optionally with SNS notification. Use for long articles, audiobook chapters, training modules, and server workflows that should not hold an HTTP audio stream open. Input limit is 200,000 total characters, with no more than 100,000 billed characters. Documented fact: https://docs.aws.amazon.com/polly/latest/APIReference/API_StartSpeechSynthesisTask.html
• StartSpeechSynthesisStream: bidirectional streaming input/output over HTTP/2. Use only when the application needs streamed generative audio while text is still arriving. Documented fact: AWS currently documents this operation as supporting only the generative engine and not JSON speech marks. Source: https://docs.aws.amazon.com/polly/latest/APIReference/API_StartSpeechSynthesisStream.html

Then select the engine: