Watson Natural Language Understanding

Overview

IBM Watson Natural Language Understanding analyzes text — sentiment, entities, keywords, categories, and emotions. Auth is an IBM Cloud API key (an unauthenticated request returns 401, verified).

Quick Start

Get an IBM Cloud API key, then (replace YOUR_KEY):

curl -X POST "https://api.us-south.natural-language-understanding.watson.cloud.ibm.com/v1/analyze?version=2022-04-07" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -d '{"text": "I love this product!", "features": {"sentiment": {}}}'

{ "usage": { "text_characters": 19, "features": 1 }, "sentiment": { "document": { "score": 0.9, "label": "positive" } } }

Authentication

• Register at cloud.ibm.com → create a Natural Language Understanding instance → API key.
• Get an IAM token: curl -X POST https://iam.cloud.ibm.com/identity/token -d "grant_type=urn:ibm:params:oauth:grant-type:apikey&apikey=YOUR_KEY" → access_token.
• Send as Authorization: Bearer {token} (missing → 401, verified).

Rate Limits & Notes

• Free tier: 30,000 NLU items/month (check the docs); paid plans scale.
• Features: sentiment, entities, keywords, categories, concepts, emotion, relations.
• The version=YYYY-MM-DD query param is required.

FAQ

Is Watson NLU free? Free tier: 30,000 items/month; more is paid.

How do I get a key? IBM Cloud → create an NLU instance → API key.

What’s the auth flow? Exchange the API key for an IAM bearer token first.