API Reference

Text Analysis API

Analyze text for sentiment, keywords, readability, and more. 20 free requests/day — no account needed.

Base URL

https://your-domain.vercel.app/api/v1

Authentication

Free tier: no authentication required (20 requests/day, 2,000 chars max).
Pro tier: include your API key in the Authorization header.

Authorization: Bearer qs_YOUR_API_KEY

Endpoints

POST/api/v1/analyzeAnalyze text

Request body

{
  "text": "Your text to analyze here..."
}

Example request

curl -X POST https://your-domain.vercel.app/api/v1/analyze \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer qs_YOUR_API_KEY" \
  -d '{"text": "The product is absolutely fantastic and I love using it every day."}'

Response

{
  "ok": true,
  "tier": "pro",
  "data": {
    "wordCount": 14,
    "sentenceCount": 1,
    "characterCount": 69,
    "readingTimeSeconds": 5,
    "sentiment": {
      "score": 0.842,
      "label": "positive",
      "comparative": 0.2105
    },
    "readability": {
      "fleschKincaidScore": 72.4,
      "gradeLevel": "7th grade"
    },
    "keywords": [
      { "word": "product", "frequency": 1, "relevance": 1 },
      { "word": "fantastic", "frequency": 1, "relevance": 1 },
      { "word": "love", "frequency": 1, "relevance": 1 }
    ],
    "topSentences": [
      "The product is absolutely fantastic and I love using it every day."
    ]
  }
}

GET/api/v1/analyze?text=...Quick analysis (2,000 chars)

curl "https://your-domain.vercel.app/api/v1/analyze?text=Great+product!"

Response fields

Field	Type	Description
wordCount	number	Total words in the text
sentenceCount	number	Number of sentences detected
characterCount	number	Total character count
readingTimeSeconds	number	Estimated reading time at 200 WPM
sentiment.score	number (-1 to 1)	Overall sentiment score
sentiment.label	string	positive \| negative \| neutral
sentiment.comparative	number	Score per word (normalized)
readability.fleschKincaidScore	number (0-100)	Higher = easier to read
readability.gradeLevel	string	Approximate US grade reading level
keywords	array	Top 10 keywords with frequency and relevance
topSentences	array	Up to 3 key sentences by keyword density

Rate limits

Free tier

• 20 requests / day
• 2,000 characters max
• No API key required

Pro — $9/month

• Unlimited requests
• 50,000 characters max
• API key authentication

Get API key →

Error codes

Code	Meaning
400	Missing or invalid text field
401	Invalid API key
413	Text exceeds character limit for your tier
429	Daily rate limit exceeded — upgrade to Pro
500	Internal server error