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Billy Accounting Setup (BYOK) — connector documentation

  • MCP endpoint: https://byok-billy-accounting-setup.connectorbay.com/mcp
  • REST API: POST https://byok-billy-accounting-setup.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://byok-billy-accounting-setup.connectorbay.com/openapi.json
  • Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
  • Authentication: your own Billy Accounting Setup Billy access token (Settings, Access tokens), sent in the X-Upstream-Key header of every request (never stored, logged or cached)
  • Health: https://byok-billy-accounting-setup.connectorbay.com/health · Tool schemas: https://byok-billy-accounting-setup.connectorbay.com/tools.json
  • Publisher: Unify Dynamics LLC · connectorbay.com/byok-billy-accounting-setup · agent@connectorbay.com

What Billy Accounting Setup (BYOK) is for

Billy Accounting Setup (BYOK) lets an AI assistant read your own Billy Accounting Setup data through the Billy Accounting Setup API with a key you supply (Billy access token (Settings, Access tokens)). Read-only: 10 tools (list_account_groups, list_account_natures, list_tax_rates, list_tax_rate_deduction_components, list_sales_tax_rulesets, list_sales_tax_rules, list_sales_tax_returns, list_currencies, list_daybooks, list_countries). The BYOK key travels with each request, is used for that one call only and is never stored, logged or cached; it is only ever sent to api.billysbilling.com. Unofficial connector by Unify Dynamics LLC: not affiliated with, endorsed by or sponsored by Billy Accounting Setup. Billy Accounting Setup and its logos are trademarks of their owners and are used only to say which service the connector works with.

Ask your assistant things like:

  • "How are the accounts in my Billy chart of accounts grouped?"
  • "What account natures does Billy use?"
  • "What VAT rates are set up in Billy?"
  • "How is deductible VAT split into accounts in Billy?"
  • "Which sales tax rulesets exist in Billy?"
  • "Which tax rate does Billy use for customers in a given country?"

What it does

  • list_account_groups: List the account groups of the chart of accounts with name, description and the nature (asset, liability, revenue and so on) they belong to.
  • list_account_natures: List the account natures with name, report type (balance sheet or profit and loss) and normal balance side.
  • list_tax_rates: List tax rates with name, abbreviation, rate, whether they apply to sales or purchases, predefined and active flags, predefined tag, group and priority.
  • list_tax_rate_deduction_components: List the deduction components of tax rates: the tax rate id, the share deducted, the source, the account it posts to and the priority.
  • list_sales_tax_rulesets: List sales tax rulesets with name, abbreviation, description, fallback tax rate id and predefined flag.
  • list_sales_tax_rules: List the rules inside sales tax rulesets: ruleset id, country, state, country group, contact type, tax rate id and priority.
  • list_sales_tax_returns: List VAT returns with period type, period, start and end dates, report deadline and settled and paid flags.
  • list_currencies: List the currencies with code (as name) and the exchange rate Billy uses.
  • list_daybooks: List daybooks with name, whether the transaction summary is enabled and the default contra account id.
  • list_countries: List countries known to Billy with name and flags for states, finite states and finite zip codes.

BYOK key

You bring your own Billy Accounting Setup Billy access token (Settings, Access tokens) (https://www.billy.dk/api/#authentication). Your assistant sends it in the X-Upstream-Key header with each request. ConnectorBay uses it for that one call only: it is never stored, logged or cached, never shown in an answer, and it is only sent to api.billysbilling.com over https, with no redirects followed. Create a key with the fewest permissions the tools need (read-only if the provider offers it), and revoke it at the provider whenever you like.

Data sources

Live from the Billy Accounting Setup API (api.billysbilling.com) with a BYOK key; documentation: https://www.billy.dk/api/. Endpoints checked against that documentation on 2026-10-16.

What it is not

Unofficial connector by Unify Dynamics LLC: not affiliated with, endorsed by or sponsored by Billy Accounting Setup. Billy Accounting Setup and its logos are trademarks of their owners and are used only to say which service the connector works with. It is read-only: it never creates, changes, sends or deletes anything in your Billy Accounting Setup account.

Built for: Worldwide. Languages: English.