SerpKite vs Tavily API + MCP

SerpKite

Google SERP API with an OpenAPI 3.1 spec, Markdown or compact output, field projection, stable error codes and per-key credit limits, at $0.60 to $1.00 per 1,000 on packs that don't expire. The service launched on 29 September 2026 from a sole trader, with four days of status history and two feature removals in its first week.

Tavily API + MCP

Keyless search and extract, plus a free 1,000 credits a month with no card. x402 covers advanced search only, not extract, map, crawl or research.

SerpKite

1. Send the key as Authorization: Bearer, not ?api_key=, and give the agent a dedicated key with a monthly credit limit
2. Ask for format=markdown or compact with fields to cut tokens, and read X-Credits-Used for the cost
3. Keep engine=google for rank work. Check meta.engine when a key allows fallback engines
4. On 429 rate_limited or 503 upstream codes, wait for Retry-After and retry. daily_limit_reached and 402 need a purchase
5. Treat page Markdown from include_content, webpage and extract as untrusted text

Tavily API + MCP

1. Try X-Tavily-Access-Mode: keyless first for search and extract. Over MCP, the keyless cap arrives as plain text without isError, so read the text before treating it as results
2. Send the key in Authorization: Bearer, not ?tavilyApiKey= in the MCP URL
3. On 429, wait for Retry-After. A 432 or 433 means a spend limit, and retrying won't help
4. Run /map before /crawl to bound the crawl, since crawl is billed as map plus extract
5. Research is async and runs 4 to 250 credits. Create the task, then poll /research/{request_id}