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Amazon Lex vs Rasa

Amazon Lex logo

Amazon Lex

Software

AWS conversational AI service

From
$0.00075/per text request
Rated
-
Full reviewWebsite
Rasa logo

Rasa

Software

Open-source framework for building conversational AI

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Rasa has a free tier, so it costs nothing to try first.
  • Each has a real cost: Amazon Lex pay-as-you-go model with no standard free tier, only AWS free credits for new customers (6 months, $200 limit); Rasa free Developer Edition caps conversations at 1,000 external or 100 internal per company per month
  • They diverge on capability: Amazon Lex covers Speech recognition, Rasa covers NLU engine.

Where they differ

Only the attributes on which Amazon Lex and Rasa actually diverge.

Attributes where Amazon Lex and Rasa differ
AttributeAmazon LexRasa
Starting price$0.00075/per text requestFree
Pricing modelusage-basedopen-source
Free tierNoYes
PlatformsWeb, AWS CloudOn-premise, Cloud deployment, Docker, Kubernetes
Founded20062016

Identical on both: user rating (Not yet rated), category (Unknown).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Amazon Lex

  • Speech recognition
  • Natural language understanding
  • Voice and text
  • Lambda integration
  • AWS services
  • Lambda
  • DynamoDB
  • SNS

Only in Rasa

  • NLU engine
  • Dialogue management
  • Multi-language support
  • Testing tools
  • Slack
  • Teams
  • Custom channels
  • API

What people use each for

The jobs each tool is most often brought in to do.

Amazon Lex

  • Building conversational chatbots leveraging Alexa deep learning enginenot Rasa
  • Voice and text-based NLU applications requiring automatic speech recognitionnot Rasa
  • Custom conversational interfaces integrated into existing applicationsnot Rasa

Rasa

  • Developers self-hosting an open source conversational AI framework before needing enterprise scalenot Amazon Lex

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Amazon Lex

  • Pay-as-you-go model with no standard free tier, only AWS free credits for new customers (6 months, $200 limit)
  • Speech requests cost $0.004 each, text requests $0.00075 each, training costs $0.50 per minute
  • Variable costs can accumulate quickly for high-volume applications

Rasa

  • Free Developer Edition caps conversations at 1,000 external or 100 internal per company per month
  • Rasa Pro and the Business Plan (Pro plus Studio) are not priced on the site and require contacting sales

Pricing, plan by plan

Amazon Lex

$0.00075/per text request

No published plan breakdown. See the Amazon Lex review.

Rasa

Free
  • Open SourceFree
    • Full framework access
    • Community support
  • Rasa Pro$50/month
    • Additional tools
    • Priority support
  • Enterprise$undefined/month
    • Advanced features
    • Dedicated support

Which should you pick?

Choose Amazon Lex if

  • You need speech recognition.
  • You work on Web, AWS Cloud.
  • You also want natural language understanding.
Amazon Lex review

Choose Rasa if

  • You need nlu engine.
  • You want to start without paying.
  • You work on On-premise, Cloud deployment, Docker, Kubernetes.
  • You also want dialogue management.
Rasa review

Questions people ask

Is Amazon Lex or Rasa better?
Neither clearly leads. Amazon Lex starts at $0.00075/per text request and Rasa at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Amazon Lex or Rasa?
Rasa has a free tier; the other does not. Paid plans start at $0.00075/per text request for Amazon Lex and Free for Rasa.
Does Amazon Lex or Rasa run on more platforms?
Amazon Lex runs on Web, AWS Cloud. Rasa runs on On-premise, Cloud deployment, Docker, Kubernetes.
Can I use Rasa for free?
Yes. Rasa has a free tier, so you can try it without paying. Amazon Lex starts at $0.00075/per text request.
What is Amazon Lex best used for?
Amazon Lex is most often used for building conversational chatbots leveraging alexa deep learning engine, voice and text-based nlu applications requiring automatic speech recognition, custom conversational interfaces integrated into existing applications. Of those, building conversational chatbots leveraging alexa deep learning engine and voice and text-based nlu applications requiring automatic speech recognition are not what Rasa is typically brought in for.
What can Amazon Lex do that Rasa cannot?
Amazon Lex covers Speech recognition, Natural language understanding, Voice and text, Lambda integration. Rasa covers NLU engine, Dialogue management, Multi-language support, Testing tools.
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