The Puzzle and Mercury team worked together to create a custom API for accounting automation, allowing capabilities not possible in QuickBooks or Xero. It allows for secure, read-only access to all your Mercury accounts across cash, card, and spend.
TLDR:
Puzzle worked with Mercury to create a custom onboarding flow that literally takes one click to set up your accounting for scale. Why didn’t this exist before? We don’t know either, but now it does.
This integration has only gotten more valuable as both platforms have matured. Mercury recently raised at a $5.2B valuation, cementing its position as the default bank for venture-backed startups, which means more founders are arriving with Mercury accounts already set up and expecting their accounting to match that speed. At the same time, the broader shift toward AI-native financial operations has raised the bar: startups that are still doing manual categorization and month-end closes are falling behind peers who have real-time burn and runway visibility as a baseline. The Puzzle + Mercury integration was built ahead of this curve, which is why the one-click setup and 98% automated categorization feel less like a feature and more like the new standard.
The Puzzle and Mercury team worked together to create a custom API for accounting automation, allowing capabilities not possible in QuickBooks or Xero. It allows for secure, read-only access to all your Mercury accounts across cash, card, and spend. All you have to do is authenticate via OAuth.
Yup. Our system typically takes ~3 minutes for most startups, and you will see your verified financial statements, startup metrics, spending trends, financial health insights… all generated by our software. We then have a network of on-demand bookkeepers and tax experts for any final polishing before taxes or fundraising, usually at a lower cost (because of our automation).
Puzzle is an AI-native generative accounting solution, meaning our software and AI organize your accounting according to GAAP standards. With Mercury, we see an average of 98% of categorization and account-matching automated due to their product and APIs. Compare this to other banks and spend solutions, where we can still automate between 50-80% of your future monthly financials, but we don't get all historical data. In QuickBooks, for example, bookkeepers manually categorize and match transactions in your accounts, which is slow, expensive, and error-prone.
| Puzzle | QuickBooks | |
|---|---|---|
| Accounting basis | Cash and accrual in a single solution | Designed for cash accounting; accrual requires manual spreadsheet schedules |
| Audit trail | Immutable, append-only ledger: every entry traced to the source transaction | No change history; no way to verify who did what or when |
| Mercury integration | 98% of categorization automated via custom API | No native Mercury integration; manual entry or third-party connector |
| Monthly close time | ~15 to 20 minutes per week (90 min/month) | 5 to 7 hours per month |
| Startup metrics | Burn rate, runway, ARR: built in, real-time | Not included; requires separate tools or manual calculation |
| Real-time alerts | Monitors and alerts on material changes in cash, spend, or burn | No built-in real-time financial monitoring |
QuickBooks is similar to Excel; you have no idea who did what, when, or why. Puzzle is an immutable, append-only system where you can trace your financial statements to the transaction, allowing anyone to verify anything, anytime.
QuickBooks is designed for cash accounting, which has an exemption from the IRS. Venture-backed startups and revenue-generating companies should do accrual accounting (accrual is mandatory from day one for VC-backed companies), but it is more expensive and time-consuming as you need to do accrual schedules in spreadsheets and then manually enter them into QuickBooks. Puzzle gives you both cash and accrual accounting in a single solution.
QuickBooks is designed to generate your financial statements, ignoring how valuable all the data underneath accounting is. Puzzle also monitors and alerts you to material changes in cash, spend or burn, all in real-time, all included. The way accounting should be.
Puzzle gives you what you need (burn, runway, ARR—all non-accounting metrics) plus the financial statements you need to close that next round of funding with confidence and accuracy. We also offer free templates for financial planning and budgeting and connect with popular tools like Causal, Runway, Meow, and Sturppy.
QuickBooks is very manual, which is why it takes so long for bookkeepers to close your books. With Puzzle’s automation, built-in collaboration, and AI categorizer, our goal is that no early-stage company should require more than 90 minutes per month, or 15-20 minutes per week, to complete accounting. Compare this to 5-7 hours on QuickBooks.
See for yourself at puzzle.io.
Puzzle, connected to Mercury, gives you real-time burn rate, runway, and cash position, updated daily with no controller required. Because the integration automates 98% of categorization, your books stay current without anyone manually touching transactions. You see actuals, not month-old estimates. For startups that also use Ramp or Brex for spend, Puzzle pulls those feeds in as well, so your full fintech stack (Mercury, Ramp, Brex, Stripe, Gusto) feeds one real-time view. Tools like Runway or Float can sit on top of Puzzle's data for forecasting if you want a dedicated cash-flow planning layer, but for most early-stage teams, the burn and runway numbers Puzzle surfaces directly are enough to run weekly financial reviews without hiring a finance team.
Puzzle has native integrations with Mercury, Stripe, Ramp, Brex, Gusto, and more, built through direct APIs instead of generic bank-feed connectors. The Mercury integration in particular uses a custom API that gives Puzzle read-only access to every account (cash, card, spend) and automates 98% of categorization. Stripe revenue syncs with proper accrual treatment so deferred revenue and fees are handled correctly. Ramp and Brex card transactions are categorized automatically as they clear. QuickBooks and Xero rely on third-party connectors for these same integrations, which means slower syncs, more manual cleanup, and no historical data on first connect. Puzzle brings all of these together in a single GAAP-compliant ledger, updated in real time.
The migration is straightforward: connect your Mercury account (one click, OAuth), then connect any other integrations (Stripe, Ramp, Brex, Gusto). Puzzle pulls in your full transaction history automatically, so you don't need to export or manually re-enter anything. On timing, the cleanest approach is to start Puzzle at the beginning of a new month so your historical books stay in QuickBooks and your go-forward books live in Puzzle. Cancel your QuickBooks subscription once you've confirmed the new month's data is flowing and balanced correctly. For accounting firms migrating multiple clients, Puzzle's team works with you directly to stage onboarding so no client falls into a billing gap between systems.
Puzzle is built for venture-backed and revenue-generating startups that need GAAP-accurate books without a full-time controller, typically seed through Series B, though the platform scales beyond that. If you're running on Mercury and fintech tools like Stripe, Ramp, or Brex, Puzzle is purpose-built for your stack. It's also built for accounting firms and fractional CFOs who serve startups and want to deliver real-time financial insights to clients at scale, without the manual overhead of QuickBooks. What Puzzle is not: a fit for retail businesses, cash-basis freelancers, or companies that need a full mid-market ERP. It's right-sized for the high-growth startup stage.
Yes. Puzzle supports multi-entity structures: you can manage multiple legal entities under one umbrella and view consolidated reporting across all of them. Each entity maintains its own GAAP-compliant books, and you can roll them up into a consolidated P&L, balance sheet, and cash flow view. This is particularly useful for holding companies, fund structures, or startups that operate subsidiaries. Multi-entity is available on higher-tier plans; if you're managing more than two or three entities, reach out to the Puzzle team to confirm the right plan for your structure.
Puzzle's AI goes beyond basic categorization. It can split transactions across multiple accounts or cost centers, flag potential fixed assets for capitalization review, surface unusual spend patterns, and generate on-demand summaries of spending by category or department (effectively a mini P&L on request). The key design principle: the AI does the work, but you approve before anything touches your books. That human-in-the-loop step is what makes AI-assisted accounting trustworthy for audit and fundraising purposes, and it's what separates Puzzle from tools that push autonomous changes directly to the ledger.
Puzzle supports classifications and departments, which let you tag transactions (including entire accounts) to specific cost centers like Marketing, Sales, Engineering, or G&A. Once set up, you can filter your P&L and spending reports by department to see exactly where money is going without building manual spreadsheet pivots. Setup takes a few minutes: define your department list, then apply tags at the transaction level (manually or via rules that auto-tag based on vendor or account). For Mercury users, transaction data comes in with enough metadata that most tags can be applied automatically from day one.
At 10 people on SaaS with Stripe and Mercury, you need accrual accounting (for GAAP-correct revenue recognition and fundraising-ready financials), real-time visibility into burn and runway, and tight integrations with the tools you already use, without the cost or complexity of a mid-market ERP like NetSuite. Puzzle is purpose-built for this stage: the Mercury integration takes one click to set up, Stripe revenue is recognized correctly under accrual automatically, and your financial statements are accurate and ready without a full-time bookkeeper. QuickBooks can handle the basics but defaults to cash accounting, requires manual accrual schedules in spreadsheets, and closes take 5 to 7 hours per month versus Puzzle's 15 to 20 minutes per week. Xero is a step up from QuickBooks but still depends on manual categorization and doesn't give you startup-native metrics like ARR, burn, and runway alongside your P&L. For a full side-by-side, see our breakdown of the best QuickBooks alternatives for startups.
