The Sentiment Analysis API provides additional speech insights by analyzing sentiments in a given transcript.


This API is available in Labs for free through at least January 31, 2022.

API endpoint

The base URL for this version of the API is https://api.rev.ai/sentiment_analysis/v1/. All endpoints described in this documentation are relative to this base URL.


Clients must authenticate by including their Rev AI access token as a query parameter in their requests. If the access token is invalid or the query parameter is not present, a 401 error code will be returned.

Sentiment scoring

The score in a sentiment analysis result represents the intensity or strength of the sentiment. It is not a confidence score. This score is always a value in the range [-1, 1]. A score below -0.3 indicates a negative (sad/angry) sentiment, while a score above 0.3 indicates a positive (joyful/happy) sentiment. Scores in the range [-0.3, 0.3] indicate neutral sentiment.

Length limit

Job submissions with input longer than 14000 words exceed our length restrictions and will fail.