SpeyBooks Documentation

SpeyBooks is a programmable accounting system for UK developers and contractors. API-first, double-entry, and built for Making Tax Digital compliance.

SpeyBooks treats accounting as infrastructure, not a user interface.

What is SpeyBooks?

SpeyBooks is built around the idea that your finances should behave like a system you can reason about, automate, and audit - not a black box you click through.

At its core, SpeyBooks is:

  • API-first - 197 endpoints across 37 resources. Every feature in the web portal is available through the REST API. The portal itself consumes the same endpoints you do.
  • Double-entry by design - a PostgreSQL trigger rejects any transaction where debits don't equal credits. You cannot bypass it - not through the API, not through a bug.
  • MTD-ready - VAT return data (Box 1-9) computed directly from the ledger. HMRC recognition for direct filing is in progress.
  • No lock-in - export everything via API, CSV, or SQL. Your data is yours.
  • Deterministic - all monetary values in minor units (integer pence). No floating point. Auditable state, no hidden logic.

What you can do with SpeyBooks

Core accounting

Create invoices, quotes, contacts, and transactions through the API. Invoices support the full lifecycle: draft → sent → partial → paid → overdue, with PDF generation and email delivery. Quotes convert to invoices with one call.

All transactions are double-entry journal entries. Business events (invoices, payments, bank imports) generate the accounting entries automatically. Manual journals exist for corrections and year-end adjustments.

Banking and categorisation

Upload any bank's CSV and the Universal Ingestion Engine infers the schema automatically - column detection, balance proof, row conservation. No format dropdowns. UK presets are available for NatWest, Starling, Monzo, HSBC, Lloyds, Tide, and others.

Imported transactions are categorised by a lattice-scored inference engine that evaluates every rule, ranks by specificity, and produces an evidence trail explaining each decision. Rules self-improve: each manual categorisation creates a maximally general rule for future imports.

Reports

Profit & Loss, Balance Sheet, Trial Balance, General Ledger, VAT Return (Box 1-9), Aged Debtors, Aged Creditors, and Dashboard Summary. All reports are computed from the ledger at query time - nothing is pre-calculated or cached. All are available via API and CSV export with date range filtering.

Limited company features

Director Loan Account tracking with real-time S455 Corporation Tax exposure, Benefit in Kind calculations (HMRC average method), and year-end snapshots. Bed-and-breakfasting detection and connected persons aggregation.

Dividend declarations with retained profit checks, board minutes (PDF), dividend vouchers (PDF), tax calculator with band breakdowns, void with automatic reversal journals, and per-director summary by financial year.

Migration

Self-service migration from Xero, FreeAgent, or QuickBooks. A 5-phase orchestrated pipeline imports contacts, opening balances, invoices, and bills, then verifies your ledger balances to the penny with a mathematical reconciliation proof. No migration service. No re-keying.

Developer tools

A terminal (Developer Shell) is built into every page of the app. All 197 endpoints are discoverable via tab completion, ghost text, and the routes command. 25 clickable ID types in responses. Toggle with Ctrl+J from anywhere.

Scoped API keys with 17 granular resource:action permissions. Idempotency keys on mutations (24-hour expiry, 5xx releases the key). Stripe-style key-value metadata on invoices, contacts, transactions, and quotes. Webhooks with delivery log and retry tracking.

OmniSearch (Cmd+K) provides fuzzy search across invoices, contacts, transactions, and accounts from any page.

Security

Row-Level Security enforced at the PostgreSQL level across 25+ tables. Two-factor authentication (TOTP). Argon2id password hashing. CSRF protection, per-endpoint rate limiting, HSTS preloaded, SSL Labs A+ rating. UK data residency - all data stored in London (GCP europe-west2). Two essential cookies only. No Google Analytics, no Meta pixels, no third-party data processors. Monthly automated security reports published to speybooks.com/insights.

Who SpeyBooks is for

SpeyBooks is for developers, technical contractors, and small company directors running UK businesses who prefer APIs and automation over dashboards and wizards.

If you've ever wished your accounting system behaved more like a database and less like a spreadsheet, SpeyBooks was built for you.

SpeyBooks is probably not for you if you want a guided, button-driven UI to do everything for you, or if you're uncomfortable working with APIs and structured data. There's nothing wrong with those tools - SpeyBooks simply makes different trade-offs.

Working with accountants

SpeyBooks works best with developer-friendly accountants who value transparency, traceability, and clean ledgers. All data is exportable via API, CSV, and standard reports.

Quick links

Base URL

All API requests use the following base URL:

https://api.speybooks.com/v1

Authentication

SpeyBooks uses API keys for authentication. Include your key in the Authorization header as a Bearer token:

curl https://api.speybooks.com/v1/invoices \
  -H "Authorization: Bearer sk_live_your_api_key"

API keys support 17 granular scopes - a reporting key can read invoices and reports but cannot delete contacts or modify transactions. See Authentication for details on generating, scoping, and rotating keys.

Response format

All endpoints return a consistent JSON envelope:

{
  "success": true,
  "data": { ... },
  "meta": { "total": 47, "page": 1 }
}

Monetary values are always in minor units (integer pence for GBP). Dates are ISO 8601. IDs are prefixed: inv_ for invoices, cont_ for contacts, txn_ for transactions, acc_ for accounts, and 21 more.

See Conventions for the full contract.

Pricing

PlanPriceTrial
Sole Trader£15/month90 days (first 50 users)
Limited Company£25/month90 days (first 50 users)

No tiers. No add-ons. Full API access on every plan. Limited Company adds director management, DLA tracking, and dividend features. Card required to start the trial.

Need help?

We keep support human, technical, and honest.