> ## Documentation Index
> Fetch the complete documentation index at: https://assemblyai.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Billing and Pricing
AssemblyAI uses pay-as-you-go pricing with no contracts, minimums, or monthly subscriptions. You only pay for what you use, and failed transcripts aren't charged. For the latest per-hour rates across all models, see the [pricing page](https://www.assemblyai.com/pricing) or the [Models pricing section](/getting-started/models#pricing).
## How billing works
* Add a credit card and deposit funds into your account. Funds are drawn down as you use the API.
* Rates are listed per hour for simplicity, but pre-recorded audio is pro-rated to the exact second of audio processed.
* Credits are deducted only after a successful transcription completes. If a request errors, you aren't charged for it.
* Monitor your balance on the **Billing** page (under **Workspace** > **Settings** > **Billing** in the [dashboard](https://www.assemblyai.com/dashboard/home)) and enable [auto-pay](#how-does-auto-pay-work) to avoid service interruptions. End-of-month invoicing is available for enterprise customers.
* Set up billing alerts under **Workspace** > **Settings** > **Alerts** in the dashboard to get notified before your balance runs low.
## Payment method and invoices
AssemblyAI accepts all major credit cards. ACH transfers are available in some cases — email [support@assemblyai.com](mailto:support@assemblyai.com) to learn more.
To update the credit card on your account, log in to the [dashboard](https://www.assemblyai.com/dashboard/home), go to **Workspace** > **Settings** > **Billing**, and update your payment details. You can also click **View billing details** in the bottom-left corner of the dashboard to jump straight to this page.
To change the company information shown on your invoices, email [support@assemblyai.com](mailto:support@assemblyai.com) with the details you'd like to appear.
## Pre-recorded Speech-to-Text billing
Pre-recorded transcription is billed on the duration of the submitted audio or video file in seconds, multiplied by the hourly rate for the selected speech model. Add-on features (for example, Entity Detection or Medical Mode) are billed separately at their own hourly rates, also pro-rated to the exact second.
## Streaming Speech-to-Text billing
**Streaming is billed per session, not per second of audio**
Streaming Speech-to-Text is billed on the total duration that your WebSocket connection stays open, not on the amount of audio you send. You're charged for the entire session — including any time the connection is idle with no audio flowing — so it's important to close streaming sessions as soon as you're done with them.
Billing for streaming sessions starts when the WebSocket connection opens and stops when the session ends. This model gives you full control over cost: you can keep a stream open continuously for instant response, or open streams on demand to minimize spend.
Each open session is billed independently on its own WebSocket-open duration, so concurrent sessions accumulate billed time in parallel. For example, two streaming sessions running simultaneously for 5 minutes each — including a single call that is dual-streamed under two separate session IDs — bill as 10 minutes of total session time at the streaming rate listed in the [Models pricing section](/getting-started/models#pricing).
Follow these best practices to avoid unexpected charges:
* Always send a session termination message when your application is finished with a stream. This is what stops billing for the session.
* If a session is not closed, it will automatically close after 3 hours — and you'll be billed for the full 3 hours of session time, regardless of how much audio was actually streamed.
* Improperly closed streaming sessions are the most common cause of unexpected charges that lead to negative account balances.
For details on how to terminate a session, see the [Session termination](/streaming/getting-started/transcribe-streaming-audio) message sequence reference.
## Multichannel billing
When [multichannel transcription](/pre-recorded-audio/transcribe-multiple-audio-channels) is enabled, each channel is transcribed and billed separately. The total cost is the audio duration multiplied by the model's hourly rate, multiplied by the number of channels.
For example, a 5-minute recording with three channels is billed as 15 minutes of audio (5 minutes × 3 channels) at the selected model's rate.
## Free tier and credits
New accounts receive \$50 in free credits for Pre-recorded STT, Real-time STT, Voice Agent API, Speech Understanding, and Guardrails. Credits do not expire, and any unused credits are retained on your account when you upgrade by adding a credit card. LLM Gateway is not included in the free tier.
Once your free credits are used up, add a credit card to keep using the API. If your balance reaches \$0 without [auto-pay](#how-does-auto-pay-work) enabled, API access is paused until you top up.
## Volume discounts
If you plan to send large volumes of audio or video through the API, [contact sales](https://www.assemblyai.com/contact) to see if you qualify for a volume discount.
## Startup and Y Combinator pricing
Early-stage startups can apply for the [AssemblyAI Startup Program](https://www.assemblyai.com/startup-program), designed to help startups build with the speech-to-text API without financial constraints.
Y Combinator companies qualify for special pricing — [contact sales](https://www.assemblyai.com/contact) to discuss the discount and see if you qualify.
## AWS Marketplace
AssemblyAI is available on the [AWS Marketplace](https://aws.amazon.com/marketplace/pp/prodview-j45hta6jdej7c). Purchasing through the AWS Marketplace lets you consolidate billing with your existing AWS account and apply your spend toward any AWS committed-use agreements. For details, [contact sales](https://www.assemblyai.com/contact/sales) or ask your AWS account team.
## Billing and customer usage tracking
The **Cost** and **Usage** pages under **Workspace** > **Manage** in your dashboard provide a breakdown of spend and usage. If you need to track usage programmatically on a per-customer basis, you can use webhooks with custom query parameters for async transcription, or capture the `session_duration_seconds` from the WebSocket Termination event for streaming.
For async transcription, append a `customer_id` query parameter to your webhook URL when submitting a transcription:
```
https://your-domain.com/webhook?customer_id=customer_123
```
When the transcription completes, extract the `customer_id` from the webhook URL and retrieve the `audio_duration` from the transcript response to record usage.
For streaming transcription, manage customer IDs in your application state and capture the `session_duration_seconds` from the Termination event. AssemblyAI bills streaming based on session duration.
Creating separate API keys for each customer is not recommended. Use webhooks
with metadata instead.
## How does Auto-pay work?
Auto-pay automatically recharges your account when your balance falls below a specified threshold. When triggered, it charges your card to bring your balance back to a predetermined amount. Auto-pay is recommended for production environments to prevent service interruptions.
### Example
If you set:
* **Whenever my balance falls below:** \$25
* **Bring my balance back to:** \$50
When your balance of \$26 drops to \$21 after a \$5 charge, auto-pay will add \$29 to reach your \$50 target balance.
When your balance hits \$0 or goes negative without auto-pay, your API access is restricted until you add funds. You'll receive this error message: `{"error": "Your current account balance is negative. Please top up to continue using the API."}`
Enable auto-pay and maintain a healthy balance to ensure uninterrupted API access. Set your threshold based on your typical monthly usage to avoid frequent small charges.
You can also disable auto-pay at any time from **Workspace** > **Settings** > **Billing** in the [dashboard](https://www.assemblyai.com/dashboard/home).