> This page is for Build.

> Append .md to any page URL for clean Markdown. Index: https://docs.speechify.ai/llms.txt.
>
> Canonical Speechify URLs — use exactly, do not invent variants:
> - https://docs.speechify.ai — this site (API reference, SDKs, quickstarts)
> - https://speechify.ai — marketing + product site
> - https://platform.speechify.ai — customer dashboard, signup, API keys, billing
> - https://api.speechify.ai — API base URL
> - https://github.com/Speechify-AI: GitHub org for the API (cookbook, demos, CLI). `github.com/speechify` does not exist.
> - https://status.speechify.ai — status + incidents
> - https://speechify.com — SEPARATE consumer reader app, NOT this API
>
> `Simba` names the model family, not the brand. Model ids: `simba-3.2` (English, recommended) and `simba-3.0` (English, German, Spanish, French, Italian and Portuguese; the default). `simba-english` and `simba-multilingual` are retired: a new workspace that sends either gets `400 model_retired`. `SimbaVoice` / `simbavoice.ai` are retired.
>
> Ask, don't scrape. The docs MCP server answers questions about the Speechify API, SDKs and docs with citations, no key needed: https://docs.speechify.ai/_mcp/server (Streamable HTTP, tool `searchDocs`). Setup: https://docs.speechify.ai/build/guides/get-started/connect-mcp

# Verify Watermark

POST https://api.speechify.ai/v1/audio/watermark/verify
Content-Type: multipart/form-data

The public AI detection tool. Ask whether a clip carries the watermark
Speechify seals into audio it generates, with no account, no API key and
no credential of any kind.

`verify` answers; `detect` measures. This route returns a bare yes or no,
the way verifying a signature does. Its sibling
`POST /v1/audio/watermark/detect` takes an API key and returns the
detector's confidence alongside the verdict.

This is the programmatic half of the tool published at
\<[https://speechify.ai/detect>](https://speechify.ai/detect>), and it exists so the tool can be invoked
without visiting our website, as California's AI Transparency Act
(BPC 22757.2) requires. Nothing about the clip is stored, and nothing
identifying about you is collected or retained.

The answer is a bare verdict. `watermarked: true` is positive evidence
that the audio came from Speechify synthesis. `watermarked: false` is
NOT proof that it did not: only models redeployed since the watermark
shipped mark their output, the detector needs at least three seconds of
clear speech to judge, and re-encoding or changing the speed of a clip
degrades the mark. Treat a negative as the absence of evidence rather
than as evidence of absence.

Because the tool takes no credential, it is rate-limited per client
address and shares a platform-wide budget: expect a 429 under sustained
automated use, and retry after the interval the response advertises.
Use `POST /v1/audio/watermark/detect` with an API key for the detector's
confidence score and a per-workspace allowance of its own.

Reference: https://docs.speechify.ai/build/api-reference/v1/audio/watermark/verify

## Request

### Body (multipart/form-data)

This endpoint expects a multipart form containing a file.

- `audio` (file, required) — The clip to check, at most 25MB. Give the detector at least three seconds of clear speech; below that its answer is not worth acting on.

## Response

### 200

The clip was checked.

- `watermarked` (boolean, required) — Whether the clip carries the Speechify watermark.

## Errors

### 400 Bad Request Error

The request was malformed or failed validation. The response body is the standard `Error` envelope; for validation failures `error.fields` enumerates the offending fields as a `path -> message` map (code = `validation_failed`).

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

### 413 Content Too Large Error

Request body exceeded a per-endpoint size limit (e.g. the file upload cap, KB document upload cap, batch-call CSV cap).

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

### 422 Unprocessable Entity Error

The request was well-formed but semantically rejected - typically a referential integrity violation (e.g. flow node references an audio asset in another workspace) or a state machine refusal.

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

### 429 Too Many Requests Error

Rate limit or concurrency limit exceeded. `error.code` says which ceiling, and they need different responses: `rate_limited` is the request-rate budget (slow down), `concurrency_limit_reached` is a workspace-wide concurrency ceiling (fewer at once, or raise it), and `conversation_turn_in_progress` is contention over one named conversation (keep one message in flight on it). Every 429 carries `Retry-After` and the request-rate budget headers; the active-call cap also carries `RateLimit-Remaining-Calls: 0`.

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

### 500 Internal Server Error

An unexpected server-side error occurred. Safe to retry with exponential backoff for idempotent requests.

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

### 502 Bad Gateway Error

An upstream dependency (the TTS composer or voice-metadata service) returned a 5xx. The raw upstream detail is not forwarded - the cause is in the server log; the response is a fixed `upstream_failure` envelope. Safe to retry.

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

### 503 Service Unavailable Error

A downstream dependency is degraded or the endpoint is intentionally disabled (e.g. phone-number purchase before ops setup).

- `error` (ErrorDetail, required)
- `request_id` (string, optional) — Server-side request identifier. Echoes the `Speechify-Request-Id` response header. Stable across the request's lifetime, written to structured logs, and useful when reporting issues.

## Types

### ErrorDetail

- `code` (enum, required) — Stable machine-readable error code. Additive only: codes are never renamed, only deprecated. SDKs may map each code to a typed exception class. Status-code semantics: 4xx codes describe caller-fixable issues; 5xx codes describe server-side failures and are safe to retry with backoff for idempotent requests.
  - Allowed values: `endpoint_moved`, `bad_request`, `validation_failed`, `unauthorized`, `payment_required`, `forbidden`, `not_found`, `method_not_allowed`, `conflict`, `idempotency_conflict`, `payload_too_large`, `unsupported_media_type`, `rate_limited`, `concurrency_limit_reached`, `invalid_api_version`, `internal_error`, `upstream_failure`, `service_unavailable`, `caller_not_found`, `contact_not_found`, `contact_identifier_not_found`, `contact_identifier_conflict`, `contact_resolver_not_found`, `credential_not_found`, `credential_in_use`, `agent_not_found`, `agent_in_use`, `agent_run_not_found`, `kb_not_found`, `kb_document_not_found`, `kb_folder_not_found`, `tool_not_found`, `tool_name_taken`, `channel_instance_not_found`, `team_not_found`, `trigger_not_found`, `store_not_found`, `store_document_not_found`, `hosted_api_not_found`, `api_route_not_found`, `consumer_key_not_found`, `skill_not_found`, `skill_version_not_found`, `file_not_found`, `file_path_taken`, `file_storage_limit_reached`, `store_limit_reached`, `store_document_limit_reached`, `store_bytes_limit_reached`, `store_not_configured`, `store_document_version_conflict`, `store_document_deleted`, `entitlement_override_exists`, `hosted_apis_not_in_plan`, `skills_not_in_plan`, `voice_agents_not_in_plan`, `skill_in_use`, `skill_tool_name_conflict`, `skill_limit_reached`, `agent_skill_limit_reached`, `hosted_api_slug_taken`, `api_route_conflict`, `mount_plan_changed`, `route_output_unavailable`, `route_run_timeout`, `route_run_failed`, `route_run_limit_reached`, `route_read_limit_reached`, `route_write_limit_reached`, `hosted_api_public_refused`, `route_tool_not_readable`, `route_tool_unavailable`, `route_upstream_rate_limited`, `route_upstream_error`, `hosted_mcp_not_enabled`, `hosted_api_busy`, `conversation_not_found`, `phone_number_not_found`, `sip_trunk_not_found`, `voice_not_found`, `audio_asset_not_found`, `builtin_not_found`, `batch_not_found`, `agent_test_not_found`, `workspace_not_found`, `invite_not_found`, `project_not_found`, `cross_project_reference`, `project_has_scoped_credentials`, `project_not_empty`, `project_limit_reached`, `agent_limit_reached`, `project_too_large_to_promote`, `call_not_found`, `message_not_found`, `thread_not_found`, `call_not_active`, `relay_displaces_agent`, `brain_not_found`, `brain_in_use`, `custom_model_not_found`, `custom_model_in_use`, `insufficient_scope`, `purchased_numbers_not_included`, `phone_number_quota_reached`, `batch_calls_not_included`, `voice_cloning_not_included`, `voice_cloning_unavailable_in_region`, `consent_challenge_not_found`, `consent_challenge_expired`, `consent_challenge_already_used`, `consent_phrase_mismatch`, `consent_speaker_mismatch`, `consent_recording_unusable`, `consent_verification_unavailable`, `consent_verification_required`, `watermark_audio_unusable`, `watermark_detection_unavailable`, `workspace_last_owner`, `workspace_last_workspace`, `account_deletion_blocked`, `workspace_free_limit`, `workspace_single_owner`, `invite_email_mismatch`, `invite_already_pending`, `service_account_limit_reached`, `service_accounts_not_in_plan`, `speech_marks_unsupported`, `model_retired`, `too_many_voices`, `content_policy_violation`, `safety_identifier_blocked`, `topup_not_in_plan`, `credit_purchase_unpaid`, `credit_purchase_payment_in_progress`, `tool_config_shared`, `spend_cap_exceeded`, `spend_budget_exceeded`, `project_spend_limit_exceeded`, `project_archived`, `project_not_archived`, `project_not_purged`, `project_restore_window_expired`, `project_name_taken`, `funded_balance_required`, `agent_publish_gate_failed`, `agent_publish_gate_required`, `agent_publish_gate_unavailable`, `agent_publish_gate_tool_unreachable`, `text_channel_not_in_plan`, `channel_not_in_plan`, `text_turn_failed`, `conversation_turn_in_progress`, `conversation_closed`, `conversation_not_reachable`, `conversation_channel_bound`, `conversation_prompt_not_found`, `text_message_quota_exceeded`, `durable_runs_not_in_plan`, `tool_transport_unsupported`, `agent_config_too_large`, `agent_run_not_pending`, `agent_run_action_stale`, `share_link_not_found`, `share_link_exhausted`, `share_link_limit_reached`, `destination_not_allowed`, `international_dialing_not_enabled`, `number_not_sms_capable`, `verification_required`, `intended_use_required`
- `message` (string, required) — Human-readable explanation of this specific occurrence. Safe to surface in UI banners or pass to support. The wording can change between releases; clients should match on `code`, not on the message string.
- `fields` (map from string to string, optional) — Per-field validation errors as `path -> message`. Only present on 400 responses caused by request validation (typically code=`validation_failed`). Keys are field paths in dotted/bracket notation; values are short human explanations safe to inline-surface next to the offending form field.
- `details` (map from string to any, optional) — Structured, endpoint-specific context beyond the flat `fields` map. Present only on the few errors that carry it (e.g. the `used_by` referrer list on a credential delete-conflict); its shape depends on the error `code`. Clients that don't recognise a `details` shape can ignore it - the `code` + `message` contract is unchanged.
- `docs_url` (string, optional) — Link to the documentation that resolves this class of error, when a stable page exists. Rate and concurrency 429s link the API limits reference, which lists each plan's limits and how to raise them.

## Examples

**Request**

```json
{
  "audio": "<file: [object Object]>"
}
```

**Response**

```json
{
  "watermarked": true
}
```