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This walkthrough takes you through the core loop of the Fuse API: verify your key, search for prospects, save the results into a list, and export that list to CSV.
You will need an API key — create one in Settings → API Cockpit (details). The search-and-save step debits search credits from your workspace; check your balance first if you are unsure.
1

Verify your key

If you get a 401, the key is malformed or revoked — see authentication.
2

Preview a prospect search

Search filters are structured fields. Each entry is an object — { "status": "include" | "exclude", "value": "..." } — and GET /business/prospects/filter-options returns the accepted values per field, so you never have to guess spellings:
The response is a page of matching profiles, a scrollToken for the next page, the true match total, and an echo of the filters that ran. Previewing is the cheap way to tune filters before you commit to saving.Instead of filters you can send a natural-language query ("VPs of engineering at mid-size software companies in Germany") or a stored search’s savedSearchId — the response echoes the filters either resolved to, so you can inspect and refine them. See Build a list from search.
3

Save results into a list

When the filters look right, save matches into a list. This runs the search server-side and enriches the saved contacts asynchronously:
The 202 means the job started. Contacts appear in the list as enrichment completes — poll the next step until rows show up.
Billing note: this endpoint runs its own search and debits credits for the rows it saves. It does not reuse a previous POST /prospects/search — so preview to tune filters, then save once. Details in credits & billing.
4

Read the list

Rows carry the contact’s identity fields plus columnValues for any custom columns on the list, and the response is paginated.
5

Export to CSV

Exports are asynchronous: start a job, poll it, download the file.
The downloadUrl is a presigned link valid for 15 minutes, and the file downloads named after your list.

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Where to next

Campaigns end to end

Turn a list into an outbound campaign — manual, AI-generated, or from a template.

Upload your own contacts

Bring contacts from your CRM instead of searching.

Errors

The one envelope every failure uses, and every code you can receive.

Rate limits

Per-surface quotas and the headers that tell you where you stand.