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FilmOpen documentation

xAI: technical notes

These notes gather what xAI documents about its API, for anyone comparing platforms or building on FilmOpen. The steps for getting a key are on xAI (Grok). Every page in Sources was read on 18 September 2026.

  • Console facts. What xAI’s console showed on 18 September 2026, while an account was opened, credit bought and a key created, is marked (console).
  • “Not documented” means xAI’s pages say nothing about it.
  • The name. xAI’s documentation and console now say SpaceXAI. The API’s host, the console’s address, the keys’ prefix and the environment variable keep x.ai and xai.

Account and money

Section titled “Account and money”
  • Sign-in: a Google, X, Apple or GitHub account, or an e-mail address (console). Signing up by e-mail asked for a code sent to it; no phone or identity check was asked for (console).
  • The team: sign-up asks for a Team name and what best describes you: Hobbyist, Student, Engineer, Business or Other. Keys, credit and billing belong to the team (console).
  • Prepaid credits or monthly invoices: credits are bought in advance and usage is taken from them. Monthly invoiced billing is off by default: with the default invoiced limit of $0, requests are rejected once the credits are used up (billing).
  • Buying credit: charged when you buy it (billing FAQ). The first purchase offers Explore (free), Prototype (from $5) and Build (from $50); each only fills in the amount, which can be changed. Payment is by card (Visa, Mastercard, Discover) or Cash App Pay, with a country and ZIP code, and the invoice calls it a Single Purchase (console).
  • Auto top-up: a threshold, a top-up amount of at least $5, and an optional monthly maximum. xAI recommends it and it can be turned off at any time (billing). At the first purchase it is on, below $5, for the amount being bought, with no monthly maximum (console). An account can top up at most 200 times in 24 hours (billing). After a first payment by card with auto top-up turned off, the Billing page listed no payment method (console).
  • Refunds: none for prepaid credit, unless the law requires one (billing FAQ). Expiry of credit: not documented.
  • Tax and fees: fees are exclusive of taxes, and the customer pays any card-processing fee (enterprise terms, Fees, Payment, and Taxes).
  • Promo codes: the Billing page has Redeem promo code (console).

Keys

Section titled “Keys”
  • Where: the team’s API keys page. The console’s team/default/… addresses lead to the signed-in team’s own pages (console). Management Keys, under the team’s settings, are a separate kind of key for the management API, not for models (management API).
  • Creating one (console):
    • Name: up to 127 characters.
    • Models: All models, or a choice among the Chat, Image and Video groups. No speech model is listed.
    • Endpoints: All endpoints, or a choice among Batch, Chat, Compact, Documents, Files, Image, Models, Sample, Tokenize, Video and Voice.
    • Tokens per minute and Requests per minute: no limit unless set.
    • Expiry: No expiry, or a date.
  • The same limits by API: a key’s ACLs are api-key:endpoint:<name> and api-key:model:<name>, with * for all. The management API creates keys and rotates them; after a rotation the old secret keeps working for 24 hours by default, or up to 7 days (management API).
  • What you copy: a key starting xai-, shown once in All set, here is your API key with Copy API Key (console). Afterwards only a redacted form is shown, xai-… and the last four characters (management API).
  • The list (console): Name, Key (redacted), Spend (30d), Last used and Owner, with a menu on each row.
  • Made at sign-up? No: a new team’s dashboard offers Create your first API Key (console).
  • Checking a key: GET https://api.x.ai/v1/api-key returns the key’s own record: its ACLs, whether the key or the team is blocked or disabled, its ID, name, team and redacted form (API reference). On 18 September 2026 it answered a wrong key with 400 (invalid-argument) and a request with no key with 401 (unauthenticated:no-credentials). Whether it costs anything is not documented.

Calling the API

Section titled “Calling the API”
  • Base URL and header: https://api.x.ai/v1, with Authorization: Bearer <key> (quickstart).
  • Regional hosts: us.api.x.ai handles requests in the United States, and serves none of the image, video or voice APIs; the global host, api.x.ai, is the one for voice (regional endpoints).
  • Keys in a browser: xAI’s voice pages say never to put a key in client-side code, and to reach the WebSocket through your own server (speech to text). FilmOpen’s desktop app sends your own key from the operating system’s credential store, as it does OpenAI’s.
  • Rate limits: by tier, which rises with what a team has paid xAI since 1 January 2026 and never goes down: Tier 1 from $50, Tier 2 from $250, Tier 3 from $1,000, Tier 4 from $5,000. Voice endpoints are limited by requests per second and sessions at once: speech to text allows 10 requests a second, and 100 sessions at Tier 0 or 200 at Tier 1 (rate limits).
  • SDKs: there is none for Dart, so FilmOpen speaks the WebSocket directly.

The models FilmOpen uses

Section titled “The models FilmOpen uses”

grok-voice-transcribe-2.0 transcribes live over a WebSocket, wss://api.x.ai/v1/stt. xAI calls it its best transcription model; without model, the WebSocket uses grok-voice-transcribe-1.0 (speech to text).

  • Set in the address: model, sample_rate (8,000 to 48,000 Hz, 16,000 by default), encoding (pcm, mulaw, alaw or opus), interim_results, endpointing (0 to 5,000 ms of silence ending an utterance, 400 by default), language, and options for several channels, speakers, filler words, key terms and turn detection. Nothing is sent to set the session up.
  • Languages: 25, among them English, Spanish, Portuguese, French, German, Hindi, Japanese and Korean.
  • Price: $0.20 an hour of audio while streaming (pricing).
  • Sessions: how long one may last, or stay open without audio, is not documented.

Media in

Section titled “Media in”
  • Live audio: raw audio in binary WebSocket frames, sent at the pace it is spoken, for example in 100 ms chunks. PCM is signed 16-bit little-endian; Opus is one raw packet a frame (speech to text). FilmOpen sends 24 kHz mono PCM in 100 ms frames.
  • Control messages: {"type": "finalize"} ends the utterance in progress at once; {"type": "audio.done"} says the audio has ended.
  • A recording, not live: POST https://api.x.ai/v1/stt takes a file of up to 500 MB, in WAV, MP3, OGG, Opus, FLAC, AAC, MP4, M4A or MKV, or raw PCM, μ-law or A-law with its format given. FilmOpen doesn’t use it.

Media out

Section titled “Media out”
  • Live transcripts arrive on the same WebSocket (speech to text):
    • transcript.created when the session is ready;
    • transcript.partial, with is_final and speech_final: interim words that can still change, a chunk locked after about three seconds, and the end of an utterance;
    • transcript.done, the whole transcript, after which the connection closes;
    • error, with a message.
  • A recording’s transcript comes back with the detected language, the duration, a time for each word and, when asked, speakers and channels.
  • What xAI keeps: requests and responses, encrypted, for 30 days, for auditing suspected abuse. xAI doesn’t train on API inputs or outputs without permission. Zero Data Retention is a team setting that stores neither; it turns off some features, and every response says whether it is on in its x-zero-data-retention header (security FAQ).

Usage and cost

Section titled “Usage and cost”
  • In the console: Usage in the sidebar, and each key’s Spend (30d) on the API keys page (console).
  • When a cost is counted: at the time of the request (billing FAQ).
  • Speech to text: $0.20 an hour live and $0.10 an hour for a recording (pricing). Whether a live session is billed for the audio sent or for the time connected is not documented.

Open questions

Section titled “Open questions”
  • Is a live session billed for the audio sent, or for the time it stays open?
  • How long can a live session last, and how long can it stay open without audio?
  • What does finalize answer when no utterance is in progress?
  • Is the key check, GET /v1/api-key, always free?
  • Does a wrong key always get 400 from the key check, and never 401?

Sources

Section titled “Sources”

Read on 18 September 2026: