What’s the hardest part of freelance SEO? It isn’t the audit or the content plan. It’s getting paid for them on time, every month, without turning into a part-time collections agent. If you bill retainers, invoice per deliverable, or have a client who treats “net 30” as a suggestion, you need an invoicing tool that handles all three without a weekend of spreadsheet work. Here are seven that do, starting with Fastbooks, with pricing checked on each vendor’s own pricing page on 12 November 2026.
The three billing problems an SEO freelancer actually has
You don’t bill like a plumber, and most “best invoicing app” lists are written as if you do. Your billing usually looks like one of these, and most freelancers run all three at once:
- Retainers. The same amount on the same day every month, for ongoing SEO. You want this to go out by itself, because the month you forget to send it is the month cash gets tight.
- Deliverable invoices. A technical audit, a batch of 10 articles, a link campaign, a site migration. One-off line items, often with a deposit up front and the balance on delivery.
- Chasing late payment. The awkward email on day 35. Then the more awkward one on day 50. Automated reminders take your name off those emails, and that keeps the client relationship cleaner than you’d think.
There’s a fourth problem hiding behind the first three: client concentration. If two retainers make up most of your revenue, a late payment from one of them is a payroll problem, not an annoyance. Tom Malesic’s test for that is blunt and worth running this week. Read his agency lessons on client concentration before you pick software, because the tool can’t fix a revenue sheet that leans on one client.
Quick comparison: free plans, starting prices and the catch
Prices are the monthly list price on each vendor’s pricing page (US, checked 12 November 2026). Several run introductory discounts on top of these, so your first few months may cost less.
| Tool | Free plan? | Paid plans start at | The catch for an SEO freelancer |
|---|---|---|---|
| Fastbooks | Yes: 1 user, unlimited invoices and bills | $20/month (Pro) | Bank feeds and Stripe sync start on Pro |
| Wave | Yes: Starter, unlimited invoices | $19/month (Pro) | Automated late-payment reminders are listed under Pro |
| FreshBooks | No (free trial) | $23/month (Lite) | Lite caps you at 5 billable clients; retainers start on Plus ($43) |
| Bonsai | No (7-day trial) | $15/month per seat (Basic) | Built around contracts and projects, priced per seat |
| Harvest | Yes: 1 seat, 2 projects | $11/month per seat (Teams) | Time tracking first, invoicing second |
| Invoice Ninja | Yes: 5 clients, unlimited invoicing | $14/month (Pro) | Auto late-payment reminder emails are a Pro feature |
| Xero | No | $10/month (Simple) | Simple allows 10 invoices and Early 20; unlimited starts on Growing ($59) |
Seven invoicing and bookkeeping tools that fit how SEOs bill
Each entry says what the tool does for retainers, deliverables and late payers, what it costs, and who it suits. Fastbooks gets the longest write-up because it covers invoicing and the books in one place.
1. Fastbooks: invoices, supplier bills and the books in one free workspace
Fastbooks is accounting software for freelancers and small businesses. It covers the full loop you actually run: a quote, the invoice, the reminder when the client goes quiet, the bills you pay to your own suppliers, and the books underneath all of it. That last part is where most invoicing-only apps stop and leave you exporting CSVs for your accountant.
Here’s how it maps to the three problems above:
- Retainers: recurring invoices on any billing cycle, branded, sent by email or a public link, with payment tracked.
- Deliverables: quotes and estimates that convert into an invoice in one click. Its freelancer page walks through invoicing the deposit as soon as a quote is accepted, which is how you’d want to bill an audit or a migration.
- Late payers: reminder sequences chase overdue invoices for you, and an aged receivables report shows who is late. You can also ask its AI Accountant which clients have overdue invoices and get a plain-English answer from your own ledger.
The bookkeeping side is what separates it from a pure invoicing tool. You forward supplier bills to a Fastbooks inbox, drop in a PDF or snap a photo, and its AI reads the vendor, line items, dates and tax. Rules learn from your corrections, so your Ahrefs, Semrush and hosting charges can land in the same expense account every month. It produces 13 reports, including profit and loss, balance sheet, tax summary and aged receivables, with CSV export. It also invoices in any currency with the conversion handled, which matters the first time you land a UK or EU client.
Pricing: the Free plan covers 1 user with unlimited invoices and bills. Pro is $20/month for up to 3 users, advanced reporting, and bank feeds and Stripe sync. Growth is $50/month for unlimited users. Paid plans come with a 14-day free trial, no credit card required (Fastbooks pricing).
Best for: the solo SEO who wants invoicing and real books in one place, and doesn’t want to pay for either until the business needs bank feeds.
2. Wave: a free Starter plan, with reminders on Pro
Wave is the free option most freelancers hear about first. The Starter plan is $0 and lets you create unlimited estimates, invoices, bills and bookkeeping records. Pro is $19/month (or $190/year) and adds bank transaction import, unlimited receipt capture and automated late-payment reminders that go out 3, 7 and 14 days after an invoice is due. Pricing is shown in USD and CAD, so check availability if you’re elsewhere.
Best for: a new freelancer with a handful of clients who wants free invoicing and can live without automated reminders until Pro.
3. FreshBooks: retainers built in, if you have the clients to justify it
FreshBooks lists client retainers, automated recurring invoices, scheduled late fees and automated late-payment reminders in its feature set. The catch is the client cap. Lite ($23/month list) lets you invoice 5 billable clients, Plus ($43/month) raises that to 50 and adds retainers and proposals, and Premium ($70/month) is unlimited. Archived clients count toward the limit, so a freelancer with a long tail of one-off audit clients hits the Lite ceiling fast.
Best for: an established freelancer on Plus who bills mostly retainers and wants late fees applied automatically.
4. Bonsai: contracts, proposals and invoices in one flow
Bonsai starts before the invoice. Its plans cover proposals, contracts, a client portal, time tracking and projects, and its billing features include retainer invoices, subscription invoices and scheduled sends. Basic is $15/month per seat ($9 if paid annually), and plans run up to Elite at $59/month per seat. There’s a 7-day free trial.
Best for: a consultant who sells scoped projects and wants the proposal, the signed contract and the invoice to live in the same record.
5. Harvest: when you bill by the hour
Harvest is a time tracker that invoices, not an invoicing app that tracks time. If you sell SEO consulting by the hour, that order is right. The Free plan gives you 1 seat and 2 projects with time tracking, invoicing and expense tracking. Teams starts at $11/month per seat ($9 billed annually) and integrates with Stripe, QuickBooks Online and Xero, so you can keep your books elsewhere.
Best for: hourly consultants who need the timesheet behind every invoice line.
6. Invoice Ninja: a free tier with recurring invoices and auto-billing
Invoice Ninja is free for up to 5 clients with unlimited invoicing, and the free plan includes recurring invoices, auto-billing and a client portal. Pro is $14/month (or $140/year) for unlimited clients, custom invoice designs and automatic late-payment reminder emails. Paid plans carry a 30-day money-back promise.
Best for: a freelancer with 5 or fewer retainer clients who wants auto-billing without paying for it.
7. Xero: full accounting, with an invoice count to watch
Xero is proper double-entry accounting with bank reconciliation, sales tax, and W-9 and 1099 management in every US plan. If you pay subcontract writers or link builders, that last one matters. Bookkeeper Maya Weinreb’s rule is to get a W-9 before you pay a contractor. Simple is $10/month and Early is $27/month, but those allow 10 and 20 invoices. Unlimited invoicing starts on Growing at $59/month, with Established at $97/month.
Best for: a freelancer turning into a small agency, with contractors to 1099 and an accountant who already works in Xero.
Picking an invoicing tool for your freelance SEO business by how you bill
Start from your billing mix, not the feature list. If most of your revenue is retainers, you need recurring invoices and automatic reminders on the plan you’ll actually pay for, and Fastbooks, FreshBooks Plus and Invoice Ninja Pro all list both. Check which plan each feature sits on before you commit. If you bill deliverables, you want quotes that turn into invoices so the deposit goes out the day the client says yes. If you bill hours, start with Harvest and connect it to your books.
Then answer the questions the software can’t. What are your payment terms, and are they actually in the contract? Do you charge a late fee, or just threaten one? Who sends the third reminder, you or the tool? And if your biggest client paid 60 days late, would you still make rent? If you’re still setting up the business side, these tips for launching a freelance SEO business cover the rest of the groundwork.