---
title: "Synchronous text-to-speech synthesis"
method: POST
path: "/synthesize"
tags: ["textToSpeech"]
---

# Synchronous text-to-speech synthesis

`POST /synthesize`

Generate speech synchronously from text or SSML. Returns complete audio as base64. The model associated with the voice is selected automatically.

## Headers

- `Authorization` string, required

## Request body

- object
  - `voice_uuid` string, required — Voice UUID to use for synthesis
  - `project_uuid` string — Optional project UUID to store the clip
  - `title` string — Optional title for the generated clip
  - `data` string, required — Text or SSML to synthesize (max 3,000 characters)
  - `precision` 'MULAW' | 'PCM_16' | 'PCM_24' | 'PCM_32' — Audio precision for WAV output
  - `output_format` 'wav' | 'mp3' — Audio output format
  - `sample_rate` '8000' | '16000' | '22050' | '32000' | '44100' | '48000' — Audio sample rate in Hz
  - `use_hd` boolean — Enable HD synthesis with small latency trade-off
  - `apply_custom_pronunciations` boolean — When true, automatically applies your team's custom pronunciations to matching words in the input text. Defaults to false.

## Response `200`

Successful synthesis

- TextToSpeechSynthesizeResponse200
  - `success` boolean
  - `audio_content` string, byte — Base64-encoded audio bytes
  - `audio_timestamps` AudioTimestamps
    - `graph_chars` string[] — Grapheme characters
    - `graph_times` array[] — Grapheme timestamps [start, end] in seconds
      - number[]
    - `phon_chars` string[] — Phoneme characters
    - `phon_times` array[] — Phoneme timestamps [start, end] in seconds
      - number[]
  - `duration` number, double — Audio duration in seconds
  - `synth_duration` number, double — Raw synthesis time
  - `output_format` string
  - `sample_rate` integer
  - `title` string
  - `issues` string[]

## Other responses

- `400` — Bad request
- `401` — Unauthorized

---

[API](https://skmtc.net/resemble/apis/api-reference.md) · [All operations](https://skmtc.net/resemble/apis/api-reference/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/resemble/api-reference/versions/bce48b20dad7/schema)