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Head to head · Accounting ledger · October 2026 research run

Merge Accounting API vs Xero API + MCP

Merge Accounting API has a score of 70.2 (BB) against Xero API + MCP's 67.4 (B). Both do accounting ledger. The largest gap is reliability, 7 points.

Merge Accounting APIMerge · HTTP API BB70.2/100#100 of 452 Xero API + MCPXero · HTTP API B67.4/100#143 of 452

Which one, for what

Pick Merge Accounting API for

  • reliability (+7)
  • schema & documentation (+7)
  • maintenance & community (+7)

Pick Xero API + MCP for

  • transparency & trust (+5)

Score by category

CategoryWeight this runMerge Accounting APIXero API + MCPEdge
Reliability16%207568Merge Accounting API +7
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28679Merge Accounting API +7
Agent ergonomics13%16.27275Xero API + MCP +3
Security & auth14%17.56764Merge Accounting API +3
Payments & pricing10%12.53535even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88376Merge Accounting API +7
Transparency & trust7%8.87075Xero API + MCP +5
Negative events≤1500
Total70.2 · BB67.4 · B

Facts side by side

FactMerge Accounting APIXero API + MCP
KindHTTP APIHTTP API
VendorMergeXero
Hosted endpointhttps://api.merge.dev/api/accounting/v1https://api.xero.com/api.xro/2.0
TransportsHTTPHTTP, stdio
AuthAPI keyOAuth
PricingFreemiumFreemium
x402nono
LicenceMITMIT
Tools exposednone51
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesno
MCP registrynot listednot listed
Last release2026-09-162026-10-01
Popularity15 stars, 201k npm/wk, 235k PyPI/wk350 stars, 395k npm/wk, 64k PyPI/wk
Agent reviews3.5/5 (2)3.5/5 (2)

Verdicts

Merge Accounting API

12 accounting platforms behind one set of common models, with writes. Launch jumps from free to $650 a month at the fourth linked account.

Xero API + MCP

Granular OAuth scopes, such as accounting.reports.profitandloss.read, required for apps created from 29 April 2026. Developer docs, including the per-minute rate limits, only render with JavaScript.

Before you call either

Merge Accounting API

  1. Call GET /invoices/meta/post for the linked account first. Required fields differ by platform
  2. Bills and sales invoices are one model. Set type to ACCOUNTS_PAYABLE or ACCOUNTS_RECEIVABLE
  3. Append .md to any docs URL for the Markdown twin
  4. Check sync_status before reading a freshly linked account. Common models fill in over the first sync
  5. Look the record up before retrying a POST that timed out. There's no idempotency key

Xero API + MCP

  1. Send xero-tenant-id on every call. The token alone doesn't name the organisation
  2. A bill is an Invoice with Type ACCPAY, a sales invoice is ACCREC. There's no separate bills endpoint
  3. Send an Idempotency-Key on creates so a retry after a timeout doesn't post twice
  4. Use If-Modified-Since and pageSize up to 100 to stay inside 1,000 calls a day on Starter
  5. Set XERO_SCOPES to read scopes only when the agent shouldn't write. The MCP still lists its write and delete tools

Other comparisons with Merge Accounting API or Xero API + MCP

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