Accounting

Fastbill Data Extractor

When a new customer signs up with their Fastbill account, Vern's Fastbill extractor pulls their full accounting history — invoices, customers, products, and recurring invoices — straight into your product through a single managed migration. You don't ask them to export spreadsheets or wire up Fastbill's auth flow yourself. It's built for teams onboarding users off Fastbill and getting their books into your app on day one.

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Fastbill

SaaS API (REST)

Managed auth, retries, and throttling

Normalized JSON, CSV, and DB-ready output

Cleaned JSON, CSV, and DB-ready output

Export coverage

Know exactly what Vern pulls before you migrate.

Objects Vern extracts

Vern extracts the full set of queryable Fastbill objects (5 total), including: Customers, Invoices, Products, Recurring Invoices, and Revenues.

Output schema

Normalized JSON per object with referential keys preserved, so the relationships between your user's records survive the import. Timestamps are returned in ISO 8601. Delivered as JSON or CSV, or loaded straight into your own application database or pushed to your API — whatever your product expects.

Where it can land

Your own application database (Postgres, MySQL), a direct push to your API or webhook, or JSON/CSV files, plus another accounting system (e-conomic, FreeAgent, FreshBooks) when a user is switching tools.

Source details

Built for the source type shown above, with extractor content refreshed from the collection record.

Managed by Vern

The details you normally have to build yourself.

Authentication

API key / access token. Your user pastes their Fastbill API key once when they sign up; Vern stores it encrypted and attaches it to every request, handling header signing and retries so you never touch the raw credential. See Fastbill's authentication guide.

Pagination

Vern detects and handles Fastbill's paging model (cursor, page-number, or offset) internally and returns one consistent, de-duplicated result set — so you import a user's complete data without ever managing page tokens.

Rate limits and gotchas

Fastbill enforces its own API rate limits. Vern queues and throttles requests internally so importing a new user's data never trips a 429 — even on a large account.

API-key sources rarely surface their true rate ceilings until you hit a 429 mid-import, and many silently cap page size. Vern throttles to stay under the limit and normalizes paging so a partial pull never lands a user in your product with missing data.

API quickstart

1. Create a migration for Fastbill
curl -X POST https://app.vern.so/api/v1/migrations \
  -H "x-api-key: $VERN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "name": "Fastbill → Postgres", "source": "Fastbill" }'
→ { "migration_id": "mig_..." }
2. Generate the extraction recipe (pulls live via the Fastbill API)
curl -X POST https://app.vern.so/api/v1/migrations/$MIGRATION_ID/runs \
  -H "x-api-key: $VERN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "kind": "generate", "extract_via_api": true }'
3. Run the approved extraction
curl -X POST https://app.vern.so/api/v1/migrations/$MIGRATION_ID/runs \
  -H "x-api-key: $VERN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "kind": "execute" }'
4. Download the normalized CSV export
curl https://app.vern.so/api/v1/migrations/$MIGRATION_ID/exports/{template} \
  -H "x-api-key: $VERN_API_KEY" -o fastbill_export.csv

A cleaner way to extract without rebuilding source-specific plumbing.

View docs

Common questions

Can I keep a user's Fastbill data in sync after the first import? Vern supports re-running an import on demand; incremental change tracking depends on what Fastbill's API exposes for each object.

Can I move a user from Fastbill to e-conomic? Yes — Vern normalizes the Fastbill data model into typed tables that map cleanly onto e-conomic and into your own product.

What does it cost to read the Fastbill API? Fastbill's own API access follows Fastbill's pricing/plan; Vern is billed separately per import. Check Fastbill's developer docs for their current limits.