Amazon Lex is a service for building conversational interfaces into any application using voice and text. With Amazon Lex, you pay only for what you use. There is no upfront commitment or minimum fee. Amazon Lex bots are designed for a request and response interaction or a continuous streaming conversation. With the request and response interaction, each user input (voice or text) is processed as a separate API call. In a streaming conversation, all user inputs across multiple turns are processed in one streaming API call. Pricing for Lex is based upon these two interaction models.

With streaming conversation, the bot continuously listens and can be designed to respond proactively. For example, you can configure the bot to keep a conversation going when the user needs more time to respond by sending periodic messages such as “Take your time. Let me know once you are ready.” The request and response model is a different user experience where a user input is required as a trigger.

You can try Amazon Lex for free. From the date you get started with Amazon Lex, you can process up to 10,000 text requests and 5,000 speech requests or speech intervals per month for free for the first year.

Request and Response Interaction Pricing

Key terms

Speech request: Each speech input from the user is counted as a speech request.
Text request: Each text input from the user is counted as a text request.

Pricing Example

Consider a bot that processes 8,000 speech requests and 2,000 text requests in one month.

Input requests Cost per request Number of requests Total
8,000 speech requests $0.004 8,000 requests $32.00
2,000 text requests $0.00075 2,000 requests $1.50
Total Amazon Lex charges for the month   $33.50

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