Clerk bills a retained user, not simply an active one

The workload

Clerk targets teams smaller than Auth0's enterprise tiers, and it staffs the same workload, sign-up, session management, multi-factor prompts, behind a unit it calls a Monthly Retained User rather than a monthly active user. Clerk's own pricing page, as retrieved on 16 September 2026, states a verified definition: an MRU is "a user who visits your app in a given month at least one day after signing up," and a first-day-only visitor does not count toward billing. The operator's task is narrower than watching raw sign-ups; it is watching returning users, since one-time signups do not move the bill.

What the documents show

The pricing page states a verified free Hobby-tier allowance of "50,000 MRU limit per app" with no monthly charge, alongside a "First Day Free" policy excluding same-day visitors entirely. A second Clerk document, its Organizations overview, extends the logic to a second unit: a Monthly Retained Organization is one with "at least two members" where one is an MRU, and free plans include "up to 50 MROs in development and 100 in production." Both documents are Clerk's own text and both are verified. Compared only on unit design, not on Auth0's figures documented elsewhere in this batch, Clerk's MRU model excludes exactly the users a calendar-month MAU definition would still count: a signup who never returns.

The operating cost

Clerk's verified paid tiers: Pro at $25 per month, $20 billed annually, and Business at $300 per month, $250 billed annually; Enterprise is custom, annual-billing-only. Above the free 50,000 MRUs, overage is tiered: $0.02 per additional MRU from 50,001 to 100,000, stepping down to $0.018 from 100,001 to 1,000,000, and lower again at higher volumes. Organizations carry their own overage past the free MRO allowance, starting at $1 per month per organization from 101 to 1,000. Enterprise SSO connections are billed separately again, at rates this batch's WorkOS entry documents. Whether Clerk beats Auth0 at a given user count depends on how many users return after the first day, a comparison this entry does not run, since doing so for an unstated base would be an estimate this document does not supply.

The stop condition

Clerk's page states a one-month grace period after crossing 50,000 MRUs "so your application can continue to operate correctly" before an upgrade is required, a named, verified stop condition rather than an immediate cutoff. Beyond that grace period, the condition is the same as any tiered vendor: the point at which the next overage bracket costs more than switching plans or providers.

• What share of this app's signups return after the first day, since only they count toward the bill?
• Does the product need organizations for B2B teams, a second, separate usage meter?
• Is the one-month MRU grace period enough runway to migrate before the next bracket applies?

Clerk's MRU unit and Auth0's MAU unit measure different things by design; a dollar comparison between them requires knowing the retention behaviour of a specific app's users, which neither pricing page supplies.