TL;DR: Wave's accounting software is free, but the money it makes on payment processing (2.9% + $0.30 per transaction) and payroll ($20-40/mo plus $6/employee) adds up fast, and its rule-based categorization tends to break down once you have more than one account. Prosper costs a flat $29/mo with no per-transaction cut, built to catch what a rule-based system misses. Which one costs less depends on your transaction volume and account setup, not just the sticker price.
Why Wave's accounting software costs $0
Wave Accounting is free, full stop -- invoicing, bank connections, basic reports, no monthly fee. That's not a bait-and-switch; Wave has run this way since 2010, and H&R Block bought the company in 2019 specifically because millions of small businesses already used it. The software itself isn't the product Wave sells.
The product is payment processing and payroll. Wave Payments charges 2.9% + $0.30 per card transaction (3.4% + $0.30 for Amex), and Wave Payroll runs $20/mo plus $6 per employee in self-service tax states, or $40/mo plus $6 per employee where Wave files your payroll taxes for you. Those numbers were accurate as of our last review of Wave's pricing page -- check current rates before you budget against them. For a founder who doesn't use Wave Payments or Wave Payroll, the software really is free. For one who does, it isn't.
That's a reasonable business model, and it's worth saying plainly: Wave isn't a scam or a trick. Plenty of freelancers and very small operations run on Wave for years without paying it a cent beyond a card swipe fee here and there. The math only shifts once your business starts generating enough transaction volume, account complexity, or payroll headcount that the free software starts costing you in ways that don't show up on an invoice.
Where Wave's rule-based categorization runs out of road
Wave categorizes transactions with bank rules: if the description contains "AWS," file it under software; if it contains "Delta," file it under travel. That works fine when your vendor list is short and stable, which describes most solo founders in month one.
It stops working once your transactions stop looking like clean, single-purpose line items. A few examples show up in most founders' books within the first year:
Wave doesn't flag any of these for a second look -- it applies the rule and moves on, so a miscategorization can sit in your books until someone, usually you, catches it during a manual review right before a CPA deadline.
- A Stripe payout that bundles revenue, processing fees, and a refund into one bank deposit, which a rule can't split apart
- A contractor invoice paid partly from a business card and partly from a personal card during a cash crunch
- A transfer between a Mercury account and a Brex or Ramp card that looks like income to a rule built for one-directional transactions
- A vendor that changes its billing descriptor, which is common when a SaaS tool gets acquired or rebrands
- A one-off purchase that matches an existing rule but belongs in a different category this time
The time cost that doesn't show up on Wave's pricing page
Manual review is the real price of "free." Any transaction a rule gets wrong, or any transaction with no rule at all, becomes something you have to open, read, and re-file by hand. For a founder running a handful of accounts -- a Mercury checking account, a Stripe balance, maybe a Brex or Ramp card -- that tends to be a recurring task, not a one-time setup chore.
Put a number on your own time and the math gets uncomfortable fast. If your time is worth $100-200 an hour building product or talking to customers, even a modest amount of manual categorization each month is expensive in a way that doesn't show up as a line item -- it just shows up as time spent somewhere other than the business. Results vary based on transaction volume and how consistent your vendors are, but the pattern holds: software with more manual review time isn't automatically cheaper than software with less, even when the sticker price says otherwise.
This is also the part of the comparison that's easiest to underestimate going in. A founder setting up Wave for the first time sees a clean dashboard and a few obvious rules, and it feels like the categorization problem is solved. It's only a few months in, once the transaction mix has gotten messier and the rules haven't kept up, that the manual cleanup starts eating into a Saturday instead of a spare ten minutes.
What gets lost once you're past a handful of accounts
Wave was built for a business with one bank account and maybe one credit card. Once you add a second operating account, a payroll-funding account, a couple of cards from different issuers, and a Stripe or Shopify balance, reconciliation stops being a five-minute task.
Multi-account reconciliation is where a lot of solo founders quietly fall behind on Wave -- not because the software is broken, but because it wasn't built to flag which of several accounts has the unreconciled transaction. Xero and QuickBooks Online handle multi-account setups better than Wave does, but they come with their own learning curve and, in QuickBooks' case, a price that climbs well past Wave's $0 as you add users or features.
1099 season exposes a similar gap. Wave can track contractor payments, but pulling a clean, CPA-ready 1099-NEC list at year-end depends on contractor payments having been categorized correctly throughout the year -- which loops back to the categorization problem above.
None of this means Wave is a poor product for what it's built to do. It means the free tier has a ceiling, and that ceiling tends to show up right around the point where a solo founder's business starts looking less like a side project and more like a company with real cash flow to track.
The signs it's time to stop paying with your time
There's no single transaction count where Wave "breaks." It's more that a few signals tend to show up together, and any one of them is a reasonable prompt to look at what upgrading actually costs versus what staying costs.
- You're spending more than an hour a month fixing miscategorized transactions instead of reviewing a short exception list
- You have three or more connected accounts (bank, card, and payment processor) and reconciliation regularly slips past the month it happened in
- Your CPA keeps sending back the same corrections quarter after quarter
- You've started paying yourself through payroll and Wave Payroll's per-employee fee is now a recurring line item, not a hypothetical
- You're spending time explaining your books to a bookkeeper or CPA instead of handing over something already close to clean
What $29/mo buys instead
Prosper costs $29/mo, flat, with no per-transaction cut and no payroll upsell -- it doesn't do payroll at all, so it isn't trying to make money off it. It connects to your accounts through Plaid, the same connection layer Mercury, Brex, and most modern business banks use, and applies auto-categorization across each connected account, not just one at a time.
The difference from Wave's rule-based approach shows up in what happens when something doesn't fit cleanly. Instead of silently applying a rule and moving on, Prosper is designed to surface the transactions it isn't confident about for exception-based review, so your attention goes to the handful of line items that actually need a human decision rather than a full manual pass over everything.
That's a meaningful shift in what you're paying for. Wave charges nothing for the software and collects on the back end through payments and payroll; Prosper charges a flat fee and aims to keep your review time down instead of monetizing your transaction volume. Neither model is free -- one is priced in dollars, the other in founder time -- and which one costs less depends on your own transaction volume and how many accounts you're juggling.
Laid side by side, the trade-off looks something like this:
- Wave: $0/mo software, 2.9% + $0.30 per card transaction through Wave Payments, $20-40/mo plus $6/employee for Wave Payroll
- Prosper: $29/mo flat, no per-transaction fee, no payroll product to upsell
- Wave: rule-based categorization applied silently, errors found during manual review
- Prosper: auto-categorization with exception-based review, designed to route uncertain transactions to you instead of past you
- Wave: reconciliation across multiple accounts is a manual, account-by-account process
- Prosper: Plaid-connected accounts are pulled into one view for reconciliation
Wave vs Prosper: the honest comparison
Wave still makes sense for some businesses -- genuinely low transaction volume, a single bank account, no payroll, and a founder who doesn't mind an occasional manual review pass. If that's your setup today, switching to a $29/mo tool for its own sake doesn't buy you much.
Where Prosper tends to make more sense is multi-account setups, meaningful monthly transaction volume, or a founder already paying for Wave Payments or Wave Payroll who would rather pay one flat fee than a percentage of revenue plus a per-employee charge. The comparison isn't "free vs. paid" so much as "pay in fees and time vs. pay a flat fee" -- and the right answer depends on what your books actually look like this month, not what they looked like when you started on Wave.
Either way, the decision is worth revisiting periodically rather than set once and forgotten. A setup that made Wave the obvious choice at launch can look different a year later once payroll, a second bank account, or a payment processor has entered the picture -- and the cost of staying on the wrong tool tends to be measured in hours, not dollars.
Prosper is bookkeeping software and does not provide tax or legal advice. Consult a qualified professional for tax advice. Results vary based on transaction volume, data quality, and workflow setup.