API Documentation

Use the Similar Companies API to programmatically find competitors and lookalike companies for any domain, powered by multiple AI models.

Enterprise plan required. API access is available on the Enterprise plan ($100/month). Generate an API key from Account Settings → API Keys.

Authentication

All API requests require a Bearer token in the Authorization header.

Authorization: Bearer sk_live_your_api_key_here

Generate API keys from your account settings. Keys are prefixed with sk_live_ and shown only once at creation.

Errors

The API returns standard HTTP status codes. Error responses include an error field.

Status	Meaning
200	Success
400	Bad request — missing or invalid parameters
401	Unauthorized — invalid or missing API key
402	Insufficient credits
429	Rate limit exceeded
500	Server error

Search Competitors

POST /api/competitors

Find similar companies and competitors for a domain using one or more AI models.

Request Body

Parameter	Type	Description
domain required	string	Domain to search (e.g. `stripe.com`)
models required	string[]	Array of model IDs to query. See available models.
resultCount optional	number	Results per model: 10, 25, 50, or 100. Default: 100.

Example Request

curl -X POST https://yourapp.com/api/competitors \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "domain": "stripe.com",
    "models": ["spyfu-combined", "claude-sonnet-4-6", "gpt-5.4"],
    "resultCount": 100
  }'

Response

{
  "domain": "stripe.com",
  "totalCompetitors": 221,
  "likelyCompetitors": 221,
  "flaggedAsUnlikely": 0,
  "elapsedSeconds": 12.4,
  "enabledModels": ["spyfu-combined", "claude-sonnet-4-6", "gpt-5.4"],
  "competitors": [
    {
      "domain": "adyen.com",
      "company": "Adyen",
      "competitorScore": 97,
      "competitorType": "Direct",
      "confidenceScore": 98,
      "sourceCount": 3,
      "sources": ["spyfu-combined", "claude-sonnet-4-6", "gpt-5.4"],
      "likelyCompetitor": true,
      "reasons": ["High SEO overlap", "AI consensus: direct competitor"]
    }
  ],
  "perModelData": {
    "adyen.com": {
      "spyfu-combined": { "rank": 1, "confidence": "high" },
      "claude-sonnet-4-6": { "rank": 3, "confidence": "high" },
      "gpt-5.4": { "rank": 2, "confidence": "high" }
    }
  },
  "access": {
    "plan": "enterprise",
    "canDownload": true
  }
}

List Models

GET /api/models

Returns all available AI models with their credit costs and metadata.

curl https://yourapp.com/api/models \
  -H "Authorization: Bearer sk_live_..."

Search History

GET /api/history

Returns your recent searches.

Parameter	Type	Description
limit optional	number	Max results (default 20, max 100)
offset optional	number	Pagination offset

Credits

GET /api/credits/balance

Returns your current credit balance.

GET /api/credits/transactions

Returns your credit transaction history.

Available Models

Model ID	Provider	Cost (credits)
spyfu-combined	SpyFu	4
spyfu-seo	SpyFu	4
spyfu-ppc	SpyFu	4
claude-opus-4-6	Anthropic	52
claude-sonnet-4-6	Anthropic	14
claude-haiku-4-5-20250918	Anthropic	3
gpt-5.4	OpenAI	17
gpt-5.4-mini	OpenAI	5
grok-4.20-0309-non-reasoning	xAI	6
gemini-2.5-pro	Google	9
gemini-2.5-flash	Google	4
sonar-pro	Perplexity	12
sonar	Perplexity	5

Rate Limits

The API is rate limited per API key:

Limit	Window
60 requests	Per minute
1,000 requests	Per day

Rate limit headers are returned with each response: X-RateLimit-Remaining, X-RateLimit-Reset.