Search APIs differ in what they guarantee. Some guarantee coverage, some guarantee speed, some guarantee that the answer can be traced. The last one is rare, and it is the one that matters when an agent's output reaches a customer.
Two approaches anchor the ends: SearXNG, a self-hosted metasearch endpoint, and Linkup, a search API whose output is built around citations.
The short answer
Use SearXNG when you need a private search endpoint you control and can accept operating it. Use Linkup when the output must cite a source before it can be an answer. They are not substitutes; one replaces a vendor, the other replaces an ungrounded synthesis.
What each guarantees
| Property | SearXNG | Linkup |
|---|---|---|
| Data leaves your network | No | Yes |
| Per-query cost | Server only | Per search |
| Answers cite a source | Not by itself | By design |
| SLA | You | The vendor |
| Coverage | Upstream engines | Its own retrieval |
Reading the first row against the third is the whole decision. Private means you own the plumbing; provable means the provider owns the grounding.
SearXNG in practice
It aggregates results from other engines and returns JSON, which makes it a drop-in search tool for an agent. The advantages are real: no API key to leak, no per-query bill, and no tracking.
The costs are equally real. You are operating a service that queries other engines on your behalf, which means you inherit their rate limits and terms. And merged results are only as good as the engines behind them.
Linkup in practice
Linkup fetches pages, extracts the relevant section, and returns an answer tied to that source. The constraint is the feature: no source, no answer. For customer-facing output that is exactly the behaviour a reviewer wants.
The limitation is bulk work: this is a curated answer per call, not a result list to iterate over. If your agent needs twenty pages, a plain search API is the better tool.
The combination that works
A private endpoint for exploration and internal tools, plus a citation-first API for anything that leaves the building. That is not a contradiction; it is a separation of trust levels, and it is cheaper than running everything through the most expensive guarantee.
What the agent needs to know
Tell it which search to use and when. A tool description that says 'internal research' versus 'customer-facing answer' is what stops the model from choosing the wrong guarantee because the query sounded similar.
Frequently asked questions
Can SearXNG cite sources? It returns URLs you can cite; it does not verify that the page supports a claim. That is a separate step. See giving an agent web search.
Is Linkup a replacement for Tavily or Exa? It replaces the synthesis layer more than the retrieval layer. Compare search APIs for agents.
What about cost at volume? Self-hosting wins on cost per query; citation-first APIs win on review time. Count both. See search tools.
Last checked: 12 November 2026.
Related: search skills vs search APIs, searxng, and search tools.
