Integrations overview

The n8n node is not published yet

The n8n node (n8n-nodes-vieneu 0.1.0) is marked private and has never been published to npm. It is built and working, but the repository it lives in is not public, so there is no install command you can run today — contact VieNeu to get the package, and watch the changelog for the release.

Nothing else here depends on it. The MCP server, the OpenAI-compatible endpoint, the raw API, webhooks and Vapi are live and need nothing installed.

This page routes you to the right one. Each destination owns its own detail; this one deliberately repeats none of it.

Which path is yours

What you already have	How VieNeu plugs in	Where
An app that speaks the OpenAI TTS protocol — Open WebUI, SillyTavern, LobeChat, LiteLLM, anything on the OpenAI SDK	Three settings: base URL, key, voice id. No plugin, no adapter.	OpenAI-compatible apps — per-client setup and troubleshooting by symptom · endpoint reference
An AI assistant — Claude, ChatGPT, Cursor, Claude Code	A hosted MCP server: add https://api.vieneu.io/mcp, sign in with your VieNeu account, ask for speech in plain language. Nothing to install.	MCP server
n8n	A community node (self-hosted n8n, built from source), or two ready-made workflows built from n8n's own HTTP Request node that install nothing and run on n8n Cloud.	n8n node
A voice agent or phone system	Vapi has a dedicated webhook route. LiveKit Agents, Pipecat and anything else with an OpenAI TTS plugin use /v1/audio/speech with response_format: "pcm".	Vapi · LiveKit / Pipecat · Streaming
Your own code	Call /api/v1 directly — that surface is much larger than the OpenAI-shaped one.	Cloud API overview · API reference
Something that must react when a job finishes	Register a webhook instead of polling.	Webhooks

What every path shares

Base URL https://api.vieneu.io/api/v1. One key, under either header name:

Authorization: Bearer vn_sk_...
X-API-Key: vn_sk_...

vn_sk_ keys are live; vn_test_ keys behave identically but cap each request at 100 words. Any other string — sk-…, none, an empty placeholder — is a 401 before any lookup, so a client that insists on a non-empty key field must be given a real one. A Bearer token containing a dot is read as a JWT and ignored, which is why pasting one produces "API key required" rather than "invalid key". A third header, X-VAPI-SECRET, is accepted on every /v1 route — last in precedence, so an explicit header always wins. It exists because a Vapi assistant's configuration can set neither of the other two. See Authentication.

Synthesis is billed per submitted character, minimum 50, times the engine's multiplier; a request that produces no audio is refunded automatically. See Billing.

One request end to end

curl -sS https://api.vieneu.io/api/v1/audio/speech \
  -H "Authorization: Bearer $VIENEU_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"input": "Xin chào, đây là VieNeu.", "response_format": "mp3"}' \
  --output speech.mp3

Name response_format even though mp3 is the default. Only an explicit mp3 is guaranteed to be mp3: when the request never mentions a format and the worker cannot encode one, the endpoint falls back to wav rather than failing, and -sS --output discards the X-Output-Format header that would have told you. Written to speech.mp3, those are bytes your player refuses.

Omitting voice uses the first active voice on the configured default engine (see Engines — the engine also sets the price multiplier). To choose one, ask which engine is the default, then list that engine's voices:

curl -sS https://api.vieneu.io/api/v1/engines      # no key needed; find "isDefault": true
curl -sS "https://api.vieneu.io/api/v1/audio/voices?engine=<that key>" \
  -H "Authorization: Bearer $VIENEU_API_KEY"

v4 is today's default — and, since v3 was retired from the cloud API on 2026-09-24, the only engine — but the registry is the source of truth, so substitute whatever the first call reports. The retired catalogue's ids (opaque vieneu-… slugs) shared almost no space with v4's display names, so a voice saved from an unfiltered list before the retirement 400s now; pick a fresh one. Details in Getting voice ids.

What the OpenAI shape cannot reach

POST /api/v1/audio/speech, plus the GET /api/v1/audio/voices companion its voice picker reads, is the whole compatibility surface — there is no adapter to install and nothing to maintain per client. Two things live outside that shape, and if you are comparing providers they are worth testing directly rather than inferring:

• Incremental streaming. POST /v1/tts/stream, and stream_format on the OpenAI route, deliver audio as it is generated rather than as one buffered download wearing a streaming label. It is declared per engine — features on GET /v1/engines includes stream for v4; the v3 engine retired on 2026-09-24 never had it, because it handed over its chunks in a burst at the end and could not honour the latency promise. See Streaming.
• Cloned voices, usable from code. You clone a voice once in the web Studio (vieneu.io/#/clone) — the guided path that denoises the clip, transcribes it and plays it back before saving — and its clone_… id then works on POST /v1/tts and POST /v1/tts/stream like any catalogue voice. It is the one thing an OpenAI-compatible client cannot reach: a clone_… id on /v1/audio/speech is a 400.

The smaller frictions of the OpenAI shape — no GET /v1/models, unknown body fields rejected rather than ignored, OpenAI voice names unmapped, the doubled /api/v1 base-URL trap, streaming needing two fields, browser-side CORS, and which 429 came from where — all have a symptom and a fix in OpenAI-compatible apps.

Latency, honestly

On the standard plans, first audio lands in roughly 1–2 seconds. That is comfortable for read-aloud, IVR prompts, dubbing and assistants that tolerate a beat before speaking. It is not the 200–300 ms class that hard real-time conversational agents expect. Enterprise runs on a dedicated node where that ceiling is agreed per contract instead — down to ≤ 250 ms. Either way, design around the number you measure on the plan you are on — see Latency, honestly.