The affordable Perplexity Sonar API alternative
Serpex is a web search API for AI agents that returns search results and the full page content behind them as LLM-ready markdown in a single request. Perplexity Sonar API is an answer engine — it runs the search and writes the answer with a model, billed for both. Perplexity Sonar API lists $5 – $14 in request fees, plus token costs per 1,000 searches; Serpex lists $0.50 – $0.65 — about 10× lower.
Pricing verified against Perplexity Sonar API’s public pricing page on 2026-08-16. Source. Prices change — check theirs before deciding.
Pricing compared
| Serpex | Perplexity Sonar API | |
|---|---|---|
| Search, per 1,000 | $0.50 – $0.65 | $5 – $14 in request fees, plus token costs |
| Page content | Included on the same request | Token billing on top of the request fee: $1 per million in and out on Sonar, $3 in / $15 out on Sonar Pro |
| Search + content, 10 results, per 1,000 | $2.50 – $3.25 | $5 – $14 plus tokens |
| Free tier | Free credits on signup, no card required | Credits vary by plan |
Where Serpex is different
- You keep control of the model, the prompt, and the context you feed it
- No token billing stacked on top of the search fee
- Substantially cheaper when you only need retrieval, which is most RAG pipelines
Where Perplexity Sonar API is the better choice
- Returns a written, cited answer — not a result set you still have to process
- Removes a whole model call from your pipeline if a synthesised answer is what you want
- Deep Research mode runs multi-step research as a single call
Pick Perplexity Sonar API if you want a finished cited answer rather than raw retrieval, and you are happy to hand the synthesis step to their model.
What the Serpex request looks like
One call returns the results and the page content behind them. There is no second request to orchestrate.
curl -X POST https://api.serpex.dev/api/search \
-H "Authorization: Bearer $SERPEX_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"query": "how does retrieval augmented generation work",
"include_content": true,
"content_results": 5
}'Frequently asked questions
Is Serpex cheaper than Perplexity Sonar API?
Yes. Perplexity Sonar API lists $5 – $14 in request fees, plus token costs per 1,000 search requests. Serpex lists $0.50 – $0.65 per 1,000 — roughly 10× lower at list price. Verified against their public pricing page on 2026-08-16.
What is the main difference between Serpex and Perplexity Sonar API?
Perplexity Sonar API is an answer engine — it runs the search and writes the answer with a model, billed for both. Serpex returns search results and the full page content behind them as LLM-ready markdown in a single API call, which is the difference that matters for most retrieval pipelines.
When should I use Perplexity Sonar API instead of Serpex?
You want a finished cited answer rather than raw retrieval, and you are happy to hand the synthesis step to their model.
Can I get both search results and page content in one request?
With Serpex, yes — set include_content on a normal search call and each result comes back with the page converted to markdown. That costs $2.50 – $3.25 per 1,000 requests for 10 results with content, against roughly $5 – $14 plus tokens for the equivalent on Perplexity Sonar API.
Try it against your own queries
Free credits on signup, no card required. Compare the output with Perplexity Sonar API on the queries you actually run.