Google Cloud Natural Language API Reference

Use NLP analysis as an internal diagnostic for entity coverage, content sentiment, and topic classification. Do not present it as Google's E-E-A-T score, a ranking factor, or a proxy for numeric E-E-A-T weights.

Endpoint

Entities use POST https://language.googleapis.com/v1/documents:analyzeEntities. Sentiment, classification, and moderation use POST https://language.googleapis.com/v2/documents:annotateText.

Send the API key in the X-Goog-Api-Key header, not in the URL.

Features

Feature	What It Does	SEO Use
`extractEntities`	Extract people, orgs, places, events with salience scores	Topic coverage depth, entity optimization
`extractDocumentSentiment`	Document + sentence-level sentiment score/magnitude	Content tone assessment
`classifyText`	Map content to 700+ Google categories	Topic relevance verification
`moderateText`	Content safety/moderation categories	Content quality flags

Entity Types

PERSON, LOCATION, ORGANIZATION, EVENT, WORK_OF_ART, CONSUMER_GOOD, OTHER, PHONE_NUMBER, ADDRESS, DATE, NUMBER, PRICE

Each entity includes: - name: Entity text - type: Entity type - salience: Importance score (0-1, higher = more relevant) - sentiment: Per-entity sentiment (score + magnitude) - metadata: Wikipedia URL, MID (Knowledge Graph ID) - mentions: Occurrences in the text

Sentiment Scoring

Score: -1.0 (negative) to +1.0 (positive)
Magnitude: 0 to infinity (emotional intensity, higher = more emotional)
Neutral content: score ~0, low magnitude
Mixed content: score ~0, HIGH magnitude (both positive and negative)

Pricing

Feature	Free/month	Paid (per 1K chars)
Entity Analysis	5,000 units	$0.001
Sentiment Analysis	5,000 units	$0.001
Content Classification	30,000 units	$0.002
Text Moderation	50,000 units	$0.0005

One "unit" = 1,000 characters. Free tier resets monthly.

Enable the API

Go to console.cloud.google.com/apis/library
Search for "Cloud Natural Language API"
Click Enable
Billing must be enabled on the project (free tier still applies)

Uses the same API key as PSI/CrUX.