Rillet is a sales-led ERP with a CPA-led implementation and audited security reports; RareMargin is a self-serve general ledger with a published price.

Both keep the books closed through the month instead of catching up at month-end, both are built around SaaS revenue, and both have an AI assistant. They differ in how you buy them, how much is done for you, and how far the AI may go.

Rillet’s team implements the system and takes ownership of the data migration. Its website quotes 4–6 weeks led by CPAs, and support from a customer success manager and CPA team in a dedicated Slack channel. RareMargin is set up by your own team: sign up, start from your books or from a sample SaaS company with 14 months of history, and subscribe when the books are in.

Yes, for SaaS finance teams that want to start without a sales process: RareMargin is the self-serve alternative to Rillet, at $99 a month per company with a 14-day trial.

RareMargin covers the same core: a double-entry general ledger across entities and currencies, ASC 606 revenue schedules from contracts, bills and accruals, bank matching, a close checklist with continuous controls, and an AI assistant. It does not yet match Rillet’s integrations, security reports or single sign-on, covered below.

RareMargin costs $99 a month per company, with every feature included. Rillet doesn’t publish its prices; its pricing page asks you to book a demo with sales.

RareMargin’s plan includes the ledger, revenue and AR, spend and AP, cash, the close, 13 reports, the AI assistant (300 messages a month) and the API, with no per-user fee. Dodo Payments, the merchant of record, takes the payment, and a subscription can be cancelled at any time.

Rillet. It shows SOC 1 and SOC 2 Type II reports and offers SSO through Google, Microsoft Entra and Rippling; RareMargin has neither yet.

Rillet’s security page also lists AES-256 encryption at rest, TLS 1.2 or later in transit, hosting on AWS, automated monitoring and penetration tests.

RareMargin has optional two-factor sign-in, four roles (owner, admin, accountant and viewer), approval rules with segregation of duties, and a SHA-256 hash chain over every posted entry, so a change to any past entry shows. If your auditors or customers ask for a SOC 2 report today, choose Rillet.

Rillet. Its integrations page lists native connections to tools such as Salesforce, Stripe, HubSpot, Ramp, Brex, BILL and Plaid; RareMargin connects through its API instead.

RareMargin has a REST API at /v1, webhooks for 34 event types and an MCP server for AI agents. Bank transactions come in by CSV upload or through the API, because RareMargin has no direct bank connections yet. A team that wants its billing, CRM and spend tools connected without writing code is better served by Rillet today.

RareMargin’s assistant can read the books and draft entries, but it can’t post them: each draft waits in the approval queue for a person with the right role.

The same rule covers any AI agent connected through RareMargin’s MCP server. Of the 17 tools the assistant and MCP clients share, 15 only read and 2 propose a journal entry or an accrual. Agents and API keys can’t approve anything, and nobody can approve an entry they submitted.

Rillet’s assistant is Aura AI, which answers questions about the general ledger. The Rillet pages we read don’t say what Aura may change in the books, so ask in the demo.

Choose Rillet for a managed implementation, native integrations and SOC 2 reports now; choose RareMargin to start today, on a published price, with AI that only proposes.

• Rillet fits a company that wants its ERP implemented and its data migrated for it, needs SOC reports or single sign-on, or relies on integrations with tools such as Salesforce and Stripe.
• RareMargin fits a SaaS finance team that wants to try the product on its own data today, pay $99 a month per company, keep AI agents behind approvals, and connect its own tools through an API, webhooks and MCP.