Xero and Intuit are two ecosystems. Here are 9 more.

Last week we published a piece on where to build in the Xero ecosystem now that both platforms have absorbed the middle of the app stack and started metering the API.

The best replies weren’t about Xero.

They came from people pointing at everywhere else: challenger ledgers actively courting the builders and firms the big platforms are annoying, practice platforms that suddenly need a partner ecosystem of their own, and a set of distribution surfaces that didn’t exist eighteen months ago. One challenger ledger told us it is now launching four or five new partner integrations a month, mostly with developers who want an open API and a team that will build alongside them.

So here is the follow-up. Nine ecosystems beyond the big two, who is in each one, what it is actually good for, and the honest trade-off.

The short version

Now the detail.

1. The challenger ledgers

Who is in it:

• COUNT. AI-native ledger with a public partner API and developer documentation, explicit about wanting builders on top of it. Unusually, it ships practice management alongside the general ledger: task templates, a guided close, review sign-off, client portal, time and billing, in the same workspace as the client file.
• Kick. Self-driving bookkeeping with MCP read and write access on every tier, so a customer can query their own books from Claude, ChatGPT or Cursor without a partnership conversation.
• Digits. An autonomous general ledger with agents running the bookkeeping underneath it.
• Puzzle. A QuickBooks replacement pitched at startups and the firms that serve them.
• Upmarket, aimed at NetSuite and Sage Intacct: Rillet ($100m Series C in August 2026 at a $1bn valuation, more than 600 customers, over $200m raised in total), Campfire ($100m across two rounds inside twelve weeks), DualEntry and Light.

Different products, one shared position at the small business end: open by default, because openness is the only lever a challenger has against an incumbent’s install base.

COUNT is worth a second look for a different reason. Running the general ledger and the practice management system as one product is a bet that the firm’s two biggest problems, the client file and the firm’s own workflow, are the same problem. For an app vendor that changes the shape of the integration: one API reaches both the books and the work happening around them, without stitching a ledger to a separate practice system and reconciling the two. It also means COUNT is competing with Xero and Karbon at the same time, which is either ambitious or the whole point, depending on how the next two years go.

The upmarket cohort is the more interesting bet for a lot of vendors, and the money is arriving fast enough to prove it: Rillet went from a Series B in March to a $1bn valuation in August. Their customers pay real money, their finance teams have real requirements around multi-entity, revenue recognition, consolidation and close, and none of these platforms has an app ecosystem yet. Being one of the first twenty apps in an ecosystem is a position you cannot buy later.

What you get: an open API, no metered data tax on the way out, direct access to the people who write the code, and co-marketing attention that a platform with a million customers will never give a partner with two hundred.

The trade-off: volume. Nobody is switching their whole client base this year. Treat a challenger as a way to build faster, learn quicker and be early in a partner directory that will matter later, while a larger ecosystem carries your install base today.

Diligence questions: how many active organisations, how many partners are live, how many of those partners have customers using the integration weekly, and what does the platform commit to in writing about pricing and data access. A promise of openness is worth what the contract says it is worth. Ask what happens if they later build your category. The answer will not be binding, but the way they answer it tells you plenty.

2. The other incumbents everyone forgets

Who is in it:

• Sage. Expanded its developer platform in April 2026 with a more unified experience across Intacct, X3 and Active, plus an agent builder and an AI gateway for partners building into Sage workflows. Its marketplace reaches a global base in the millions of small and medium businesses.
• MYOB. An app marketplace with over 350 apps and ground in the Australian mid-market that Xero has never fully taken.
• FreeAgent. Sits inside NatWest, with a UK base that arrives through a bank rather than through an accountant.
• Reckon, IRIS and Capium. The compliance-first UK and AU stack sitting under a lot of firms that no Xerocon keynote will ever mention.

“The big two” is an Australian and New Zealand habit. Look at a UK or US client list and the picture changes.

What you get: less competition for attention, partner teams with time to talk to you, and a real answer for firms running mixed portfolios.

The trade-off: less inbound. These marketplaces convert demand, and there is less ambient demand to convert, so plan to bring your own. Our comparison of the UK, AU and US markets is the starting point for working out which of these is worth your quarter.

3. Practice management platforms

Who is in it:

• Karbon. Reported at more than five thousand firms, with a public developer centre, release notes, OData-style filtering across contacts, organisations and client groups, work items created from templates, invoices and payments, and webhook subscriptions.
• FYI. Document management and workflow automation, strong in Australia and New Zealand.
• TaxDome. Built API-first, with connections into the US tax stack.
• Canopy. Practice management, client portal and IRS transcript work.
• Financial Cents. Publishes an open API for reporting and automation.

If you sell to firms, the ledger is where your product’s data lives and the practice platform is where your buyer’s day happens. Worth noting that the two are converging: COUNT is coming at practice management from the ledger side, and Xero Partner Hub is doing the same thing from a much larger install base.

The access is better than most vendors assume. In March 2026 Karbon published a quick-reference guide written, in its own words, for developers and AI agents working with its API. A platform that documents itself for agents is telling you exactly how it expects to be integrated with.

A fast test of intent: a public developer centre with release notes means a platform that wants partners. “Email us for API access” means a platform that tolerates them. That distinction predicts your first six months better than the size of the install base.

Two things make this the most interesting channel on the list right now.

First, the maths. One firm-level decision installs you across that firm’s entire client base, which is a very different acquisition cost to convincing small businesses one at a time.

Second, the timing. These are exactly the platforms most exposed to Xero Partner Hub and Intuit Accountant Suite moving into practice operations. A platform under pressure needs a partner ecosystem that makes it hard to leave, which makes this the best moment in years to negotiate a deep integration and real co-marketing.

The trade-off: these platforms are also consolidating, and some of them will build what you do. The same control point logic applies here as anywhere: shallow integrations get replaced, embedded ones get renewed.

4. The apps that became platforms

Who is in it:

• Ignition. Proposals, engagement letters, billing and payments, with a published integrations catalogue, an API and a Zapier connection into thousands of apps.
• Anchor. Autonomous billing and collections for firms, with a client portal, QuickBooks and Zapier connections, and API access on request.
• Dext. Capture and pre-accounting, sitting between the source document and the ledger for a very large installed base of firms.
• ApprovalMax. Approval workflows over Xero and QuickBooks, with its own integrations programme.
• Fathom and Double (formerly Keeper, rebranded in October 2025). Reporting and month-end close, both sitting on top of the ledger with firm-level adoption.

This is the category most vendors overlook, and it is the one Xero and Intuit accidentally created.

An app that reaches thousands of firms is a distribution channel whether or not it calls itself one. Ignition sits at the point a client says yes and money starts moving. Anchor sits on billing and collections. Dext sits on every source document before it reaches the ledger. Each of them holds a position your product probably needs, and each has the same problem you do: the platforms are coming for the middle, so the way to stay is to become the thing that is hard to remove.

That makes them motivated. An integration that deepens their control point is worth co-marketing to them in a way that a listing in a ledger app store never will be.

Two practical notes. Several of these are already agent-callable, with Ignition and Anchor both publishing MCP servers, so the work you did to be callable by the ledgers carries straight over. And the earlier test of intent still applies: a published integrations catalogue means a platform that wants partners, while API access on request means one that will consider it. Anchor points API questions at its support team, which tells you the conversation is a conversation rather than a self-serve signup.

The trade-off: these platforms have narrower reach than a ledger and are themselves exposed to absorption. They are also the partners best placed to notice a good integration and build it themselves, since it runs on their platform and they can see the usage. Treat them as depth in a workflow you already serve, and check how many customers actually use their integrations before you build.

5. Payroll and workforce platforms

Who is in it: Gusto, Employment Hero, Deel, Rippling and ADP, each with a partner program and an accountant channel of its own.

Payroll is the most sensitive recurring data in a small business, and Gusto now powers Xero’s US payroll, which tells you how central that layer has become. These platforms sit on data that firms need and ledgers only ever see in summary.

What you get: a high-frequency data source, an accountant channel that is already assembled, and a buyer who has already accepted that payroll costs real money.

The trade-off: compliance burden and support load. Payroll adjacency means payroll expectations, and firms will hold you to them whether or not you run the payroll yourself.

6. Payments, spend and banking rails

Who is in it:

• Marketplaces and partner programs: Stripe, Airwallex, Wise, Ramp, Adyen.
• Open banking: Plaid, Basiq, Akahu.
• Ledger aggregation: Codat, Merge, Apideck.

There are two distinct plays here and they get confused constantly.

• Distribution. List in a payments platform’s marketplace and reach finance teams and businesses who never browse an accounting app store.
• Coverage. Use an aggregator so supporting six ledgers stops being six engineering projects.

The trade-off on coverage: an aggregator puts a layer between you and every platform relationship, adds cost per connection, and gives you the lowest common denominator of each API. It buys speed. It does not buy depth, and depth is what survives absorption.

7. The vertical platforms where the data is born

Who is in it: Shopify and Lightspeed in retail and hospitality, Cin7 in inventory, ServiceM8, Simpro and Tradify in trades, Deputy in rostering, and an equivalent in every other industry.

The ledger sees a summary. These platforms see the transaction, the job, the roster and the settlement, at the grain your product probably needs. If you have ever fought a general ledger for detail it was never given, the fix is to integrate upstream of it.

What you get: better data, a buyer with an urgent operational problem, and a marketplace whose customers are the small businesses your accounting-firm buyers serve.

The trade-off: you are now in a category fight you didn’t plan for, against apps built natively for that vertical. Pick verticals where the accounting angle is the hard part, which is the same logic behind building vertical depth on the ledger side.

8. The AI directories

Who is in it: OpenAI’s plugins directory, shared between ChatGPT and Codex since July 2026, and Anthropic’s connector directory for Claude. MCP support is now production-ready across Claude, ChatGPT and VS Code with Copilot, among others.

This is the newest channel and the one almost nobody in accounting has queued up for.

Anthropic’s directory runs a real review process: who owns the API, how users authenticate, what data the connector handles, whether the tools match their descriptions, and whether write actions are correctly marked. Read that list again. Ownership, authentication, data handling, accurate descriptions, correct write semantics. That is an app store review process, and app store review processes are what stand between a vendor and a distribution channel.

What you get: presence at the exact moment a business owner or an accountant asks a question your product can answer, in a directory that is still small enough to be discoverable.

The trade-off: the work is real (an MCP server, scoped tools, clean auth, an audit trail), and there is no organic demand to convert yet. The reason to do it now is that the same work makes you callable by JAX and Intuit Intelligence, so one build serves several channels.

9. Automation platforms, the side door

Who is in it: Zapier, Make, n8n, Workato and Pipedream.

Every ecosystem above has a front door with a queue at it. This is the side door.

Zapier lists thousands of apps and its developer platform is now pitched at products and AI agents as well as at end users. Build a Zapier integration and three things happen at once. You appear in a directory that accountants and operations people already search. You become connectable to platforms you have no relationship with, including several on this list that already ship Zapier connections. And you get a cheap read on demand before you spend a quarter building anything native.

That last one is the real argument. Watching which Zaps people actually build with your product is the best free market research in the ecosystem, and it tells you which native integration to build first.

The trade-off: shallow by design. A Zapier connection gives you no relationship, no co-marketing, no placement and no defensibility, and a workflow assembled in a hurry by a firm admin is fragile in a way that a native integration is not. Use it as a way to arrive and to learn, then build native where the volume shows up.

And the channels that aren’t platforms at all

Worth saying plainly, because a marketplace is only one kind of shelf.

• Professional bodies. ACCA, ICB, CPA Australia, CA ANZ, AAT and their equivalents reach the same firms with far more trust attached. Here is what they actually want from a vendor.
• Franchise and aggregator groups. One conversation, dozens of practices, a single onboarding standard.
• Outsourcing and offshore providers. They touch the workflow of hundreds of firms and nobody markets to them.
• Firm networks and communities. Slack groups, mastermind circles, regional meetups, the people other accountants copy.
• Conferences. Still the highest-intent room in the industry when you work them properly.

None of these depend on an API, a tier, or a per-gigabyte egress charge.

The nine, side by side

One row per ecosystem, in the same order as the sections above, and four things worth comparing before you commit engineering to any of them.

• Who it reaches. The buyer sitting on the other side of that platform, meaning the person who would end up paying you.
• What it takes. The real cost of entry: the build, the partner conversation, and the standard you have to hold once you are in.
• The payoff. What you get when it works, and the reason to pick this one over the other eight.

How to choose, in three questions

Where is your data born? If the detail you need never reaches the ledger, build upstream of it. No amount of ledger integration recovers data the ledger was never given.

Which market are you in, and which is next? Ecosystem choice and market choice are the same decision once you cross a border, because the ledger that dominates in one market barely registers in another. Our market sizing guide has the firm counts, ledger install bases and compliance deadlines for AMER, EMEA and APAC in one place.

Where does your buyer already spend the day? Firms live in practice management and Outlook. Small businesses live in their vertical tool and their banking app. Build where the attention already is, then connect back to the ledger.

Who needs you more than you need them? This is the question that actually predicts channel success. A platform with a gap in its product, something to prove and a partner team with capacity will co-market, introduce you and take your calls. A platform that already shipped your category will take your listing fee. Pick the ones that need you, and hold that answer lightly, because need expires. The platform that needs you this year is also the one with the best view of how well you are doing.

The warning worth keeping

Every platform on this list is an integration to build, a support surface to staff, a set of rate limits to respect and a relationship to feed. The failure mode is five shallow integrations and no advocate inside any of them, which is the same mistake vendors make with app marketplaces and then blame the marketplace for.

Two, done properly, beats five done thinly. Prove the motion on one, expand to where the same buyer already is, and treat the rest as a roadmap rather than a launch plan.

Every platform on this list can become your competitor

Worth saying plainly, because it is now the condition of the market. Xero and Intuit absorbed the middle of the stack because building that middle got cheap. The logic does not stop at the big two.

A challenger ledger with an open API, a practice platform that loves you, an app that co-markets with you: each of them can see which of their customers use your integration, how often, and for what. AI-assisted engineering has taken a credible first version down to something a platform can approve in a sprint planning meeting. The better your integration performs, the more attractive that build looks on somebody else’s roadmap.

Partner anyway, because the alternative is no distribution at all. Just price the risk in:

• Be deep in the unglamorous parts. Exceptions, jurisdictions, edge cases and audit trails take years to copy. A happy path takes a fortnight.
• Own something they cannot see. The customer relationship, the data that lives outside their platform, the workflow that spans two of them.
• Watch the signals. A platform hiring for your category, a roadmap slide, an acquisition in your space, or sudden interest in your usage numbers.
• Read the contract. Notice periods, data access commitments, and what happens to your customers if the platform changes its mind.
• Cap the concentration. When one platform carries most of your revenue, its roadmap is your roadmap.

The big two spent 2026 telling you what they intend to own. The rest of the market spent it telling anyone who would listen that they are open for business. Both of those are useful information. So is the third thing nobody puts on a slide: if your integration works well enough to matter, someone whose platform it runs on will eventually think about building it themselves.

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Choosing and building these channels is what our partnerships work covers, and founders working through it from scratch usually start with Crack the Channel. Related reading: where to build in the Xero ecosystem, getting found in the app stores, and how to build a partner program.