SpidNums vs Karbon: an honest comparison for Canadian firms

What Karbon does well

This section comes first deliberately. Karbon is a serious product with real customers, and a comparison that pretends otherwise is not worth reading.

• Best-in-class email integration and triage — Karbon turns the shared inbox into a managed work queue better than anything else in the category.
• Mature workflow automation and templates, with a large library built by an established customer base.
• Strong collaboration features for firms where several people touch the same client file.
• A deep content and community ecosystem that firms genuinely use for practice benchmarking.

Where the fit differs

These are differences in model rather than claims about missing features. Where a capability is not listed for Karbon, that means we did not verify it — not that it is absent.

• Pricing model: Karbon is per user per month. SpidNums is flat per firm. The gap widens with every seat added.
• White-label depth: SpidNums renders the firm's own name, logo, colours, emails and letterhead to clients end to end. Karbon's positioning is as the firm's internal workflow system.
• Deadline generation: SpidNums derives due dates from Canadian rules and each client's fiscal year-end and reporting cadence.
• Data residency: SpidNums hosts in Canada (ca-central-1). We make no claim about competitor hosting.

Pricing

As of July 2026, third-party pricing summaries put Karbon's Team tier at roughly USD $59 per user per month billed annually (around $79 monthly) and Business at roughly USD $89 per user per month billed annually, with a three-user minimum on Business.

SpidNums is a flat USD $1,200 per firm per year with every feature included, so the comparison turns on headcount: per-seat pricing is usually cheaper for one person and usually more expensive from the third or fourth seat. Source: Financial Cents — Karbon pricing 2026, checked 2026-07-22.

What SpidNums is, plainly

SpidNums is practice management for Canadian accounting firms: the client list, the services each client buys, the deadlines those services generate, the person who owns each one, and the engagement letter that defined the scope. It is not a general ledger, it does not prepare or transmit returns, and it does not calculate payroll — those stay in the tools your firm already files with.

The list below is the complete set of claims this site makes about the product. If a capability is not on it, we do not claim it.

• Multi-tenant white-label branding per firm — name, logo, colours, emails and letterhead
• Colour-coded SLA deadline dashboard ranked by proximity
• Aggregated reminders across tasks, service cadences and fiscal year-ends
• E-signed engagement letters with a public, no-login client portal
• Per-tenant Google Workspace integration
• Client portal
• Staff roles with confidential-client gating
• Canadian-hosted data (Supabase ca-central-1)
• Flat USD $1,200 per firm per year, all inclusive
• CSV/XLSX client import and export

Questions worth asking both vendors

Comparison grids converge because feature names converge. These six questions separate products that look identical on paper, and they are worth asking of Karbon and of SpidNums alike.

• How is a deadline generated — from a rule tied to the client's fiscal year-end and reporting period, or from a recurring task somebody configured by hand?
• When a client's filing cadence changes, is that one field or a rewrite of every future date?
• Whose brand does the client see on emails, on the portal and on a signed engagement letter — and on which plan does that become true?
• Where is client data hosted, and is tenant isolation enforced in the database or only in the application? Get the answer in writing.
• What is the total annual cost at three seats and at ten? Ask for the total, not the per-user figure.
• What comes across on migration, and what does not? Clients usually move; documents, notes and completed work usually do not.

Who should choose Karbon

A firm of forty or more people that lives in email triage should look hard at Karbon. If your operational pain is that client conversations, approvals and handoffs all happen in inboxes and nobody can see the state of a file, Karbon solves that specific problem better than we do, and the per-seat cost is the right trade.

If that describes your firm, take the other product seriously. If it does not, the practice management overview covers what SpidNums does in full.

Switching

Client lists move by CSV or XLSX export and import. Email histories, Karbon work items and internal comment threads do not migrate — a firm switching should keep read access to its Karbon archive for the retention period rather than attempting a full transfer.

SpidNums imports and exports clients as CSV or XLSX. There is no direct migration connector, so historical documents, notes and completed work do not come across automatically — plan the cutover around a period boundary rather than mid-season.