Sentiment Analyzer API

Sentiment analysis with emotion detection, confidence scores, and key phrase extraction. Single or batch mode. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "sentiment-analyzer": {
      "url": "https://sentiment-analyzer.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl -X POST "https://sentiment-analyzer.api.klymax402.com/api/analyze" \
  -H "Content-Type: application/json" \
  -d '{"text":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

Tool	Method	Path	Price	Description
text_analyze_sentiment	POST	/api/analyze	$0.005	Analyze sentiment of a single text
text_analyze_sentiment_batch	POST	/api/analyze/batch	$0.04	Analyze sentiment of up to 20 texts in batch

text_analyze_sentiment

Use this when you need to determine the emotional tone and sentiment of text. Returns structured sentiment analysis with emotion breakdown and key drivers.

Parameters

Name	Type	Required	Description
text	string	yes	The text to analyze for sentiment

Returns

• sentiment -- overall sentiment label (positive, negative, neutral)
• confidence -- confidence score 0-100
• emotions -- detected emotions with scores (joy, anger, fear, surprise, sadness)
• keyPhrases -- array of phrases driving the sentiment
• score -- numeric sentiment score from -1.0 (negative) to 1.0 (positive)

Example response:

{"sentiment":"positive","confidence":87,"score":0.73,"emotions":{"joy":0.82,"surprise":0.15,"anger":0.01,"fear":0.01,"sadness":0.01},"keyPhrases":["excellent results","exceeded expectations"]}

When to use: responding to customer feedback, reviews, or social media mentions. Essential for brand monitoring, support ticket triage, and content tone analysis.

text_analyze_sentiment_batch

Use this when you need to analyze sentiment of multiple texts at once (up to 20). Returns an array of individual sentiment results in one call.

Parameters

Name	Type	Required	Description
texts	array	yes	Array of texts to analyze (max 20)

Returns

• results -- array of sentiment objects, one per input text
• averageSentiment -- overall average sentiment score across all texts
• distribution -- count of positive/negative/neutral texts

Example response:

{"results":[{"sentiment":"positive","confidence":91,"score":0.8},{"sentiment":"negative","confidence":74,"score":-0.6}],"averageSentiment":0.1,"distribution":{"positive":1,"negative":1,"neutral":0}}

When to use: bulk analysis of reviews, survey responses, or social media feeds. Essential when comparing sentiment across multiple data points.

Example agent prompts

• "Determine the emotional tone and sentiment of text"
• "Analyze sentiment of multiple texts at once (up to 20)"

Payment

• Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
• Network: Base L2 (eip155:8453)
• Asset: USDC
• Facilitator: Coinbase CDP (primary), PayAI (fallback)
• Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

• Catalog: https://klymax402.com/llms.txt
• Full API reference: https://klymax402.com/llms-full.txt
• Live stats: https://klymax402.com/stats

License

MIT