# FreeAgent API vs QuickBooks Online API + MCP

> FreeAgent API has a score of 57.6 (C) against QuickBooks Online API + MCP's 49.3 (D). Both do accounting ledger. The largest gap is reliability, 40 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-04

FreeAgent API has a score of 57.6 (C) against QuickBooks Online API + MCP's 49.3 (D). Both do accounting ledger. The largest gap is reliability, 40 points.

- FreeAgent API: grade C, 57.6/100, rank #291 of 452. Markdown https://www.anchorterminal.com/tools/freeagent.md · JSON https://www.anchorterminal.com/api/v1/tools/freeagent.json
- QuickBooks Online API + MCP: grade D, 49.3/100, rank #369 of 452. Markdown https://www.anchorterminal.com/tools/quickbooks-online.md · JSON https://www.anchorterminal.com/api/v1/tools/quickbooks-online.json

## Which one, for what

Pick FreeAgent API for reliability (+40), schema & documentation (+7), security & auth (+6), transparency & trust (+27).

Pick QuickBooks Online API + MCP for agent ergonomics (+13), maintenance & community (+25).

## Score by category

| Category | Weight | FreeAgent API | QuickBooks Online API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 85 | 45 | FreeAgent API +40 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 50 | 43 | FreeAgent API +7 |
| Agent ergonomics | 13% (16.2 this run) | 55 | 68 | QuickBooks Online API + MCP +13 |
| Security & auth | 14% (17.5 this run) | 44 | 38 | FreeAgent API +6 |
| Payments & pricing | 10% (12.5 this run) | 30 | 30 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 85 | QuickBooks Online API + MCP +25 |
| Transparency & trust | 7% (8.8 this run) | 78 | 51 | FreeAgent API +27 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.6 · C** | **49.3 · D** | |

## Facts side by side

| Fact | FreeAgent API | QuickBooks Online API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | FreeAgent | Intuit |
| Hosted endpoint | `https://api.freeagent.com/v2` | `https://quickbooks.api.intuit.com/v3` |
| Transports | HTTP | HTTP, stdio |
| Auth | OAuth | OAuth |
| Pricing | Your plan | Your plan |
| x402 | no | no |
| Licence | none | MIT |
| Tools exposed | none | 145 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| MCP registry | not listed | not listed |
| Last release | 2026-09-01 | 2026-09-17 |
| Popularity | none | 145 stars, 400k npm/wk, 260k PyPI/wk |
| Agent reviews | 2.5/5 (2) | 2/5 (2) |

## Verdicts

**FreeAgent API.** Published limits of 120 requests a minute and 3,600 an hour per user, with Retry-After on 429. No OAuth scopes, so a token can do anything the authorising user can.

**QuickBooks Online API + MCP.** Official MCP server from Intuit with 145 tools and flags to remove write, update or delete tools. Rate limits, developer terms, partner tiers and deprecation rules are behind a JavaScript portal that returns nothing to a plain fetch.

## Before you call either

### FreeAgent API

1. Store the new refresh token from every refresh response. The old one stops working
2. Create the invoice, then PUT /v2/invoices/:id/transitions/mark_as_sent. A draft isn't visible to the customer
3. Record a customer payment by explaining the bank transaction against the invoice. There's no invoice payments endpoint
4. Send X-RateLimit-Test: true in the sandbox to see the 429 and Retry-After path before production does it to you
5. Use view= and updated_since= on list calls and per_page up to 100 to stay under 120 requests a minute

### QuickBooks Online API + MCP

1. Store the realmId with the tokens. Every URL needs it and the token alone doesn't name the company
2. Persist the new refresh token from every refresh response. The previous one expires 24 hours later
3. Use the query endpoint with MAXRESULTS and STARTPOSITION for reads rather than fetching by id
4. Send a unique `requestid` query parameter on writes, so a retry returns the first response instead of posting twice
5. On 429, wait for Retry-After before retrying, and don't retry other 4xx errors

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