Authentication Pricing Compared (2026): Clerk vs Auth0 vs Supabase Auth vs Firebase at 10K, 100K and 1M Users

At 10,000 monthly active users, all four options cost $0 on an entry plan, so the real choice starts at 100,000. There, Supabase Auth is cheapest at $25 a month because its Pro plan includes 100,000 users, Firebase Identity Platform costs $275, and Clerk costs $1,025. Auth0 quotes no price at that volume.

Every figure below is in US dollars and was read on each vendor's own pricing page on October 10, 2026. The table covers the login line only. Databases, compute and enterprise contracts are priced separately, and the sections below show where each meter starts.

Devshot data: the audience list updated September 20, 2026 counts 28,000 developers, and our data puts the open rate at 30%. This page uses 10,000 and 100,000 users because three of the four free tiers end at 50,000 users and Auth0's ends at 25,000. Ten thousand sits inside all four, and 100,000 sits past all four.

At a glance

10,000 users: every entry plan is free, and the limits differ

At 10,000 users the bill is zero on all four, so the question is what each free plan refuses. Auth0's Free plan covers 25,000 monthly active users with no card, but multi-factor authentication factors are not on it. They start on Essentials, which is $35 a month at 500 users and, at the same rate per user, about $700 at 10,000.

Clerk's Hobby plan covers 50,000 retained users per app with three dashboard seats. MFA sits on Pro at a flat $25 a month. Firebase bills MFA and phone sign-in per text message on Google's table, outside the user count.

Supabase Free covers 50,000 users, but a free project pauses after a week without activity, and only two projects can be active. A live app therefore moves to Pro. Firebase's Identity Platform is no cost to 50,000 users, so at this volume the choice comes down to features and limits, not price. Firebase review and Supabase review cover the products themselves.

100,000 users: where the bill starts

Supabase Auth is the cheapest line at this volume. Pro includes 100,000 monthly active users for $25 a month, and each user above that costs $0.00325. The Pro fee covers the whole organization, and its $10 compute credit covers one Micro instance. The full Supabase invoice, with compute and add-ons, is in our Supabase pricing breakdown.

Firebase Identity Platform costs $275 a month at 100,000 users. Google's table gives the first 50,000 users no cost and charges $0.0055 for each user from 50,001 to 100,000. We read the table band by band, but it does not say whether a band's rate covers every user or only the users inside that band. If the rate applied to all 100,000, the bill would be $550, so check the Google Cloud calculator before you commit to a number.

Clerk costs $1,025 a month at 100,000 users on monthly billing. That is the Pro fee plus 50,000 users above the included 50,000, at $0.02 each. On annual billing the base fee drops to $20, which makes $1,020. Clerk's band table gives the same answer here, because every one of those 50,000 extra users falls in the $0.02 band.

Auth0 does not quote 100,000 users. Its calculator stops at a 30,000+ step, and Enterprise is a "Contact us" button. Auth0's plan data prices Essentials at $0.07 per user from 500 users up, so 100,000 users would be about $7,000 a month. That is our arithmetic from that rate, not a quote. Professional costs more: it starts at $240 a month for 500 users, where Essentials starts at $35.

Clerk bills retained users, so count yours first

Clerk's base unit is a monthly retained user, not a monthly active user. A user counts as retained when they come back 24 hours or more after signing up. An app with 100,000 monthly actives may therefore bill a different number. Before you compare that line with anyone else's bill, count your retained users, because that is the number Clerk charges on.

Clerk's Pro plan also includes one SSO connection, and each extra connection costs $75 a month. Organizations work differently: Clerk includes 100 monthly retained organizations, and its Enhanced add-on costs $100 a month. Those lines are not in the monthly figure, so add them if you sell to companies.

At a million users, the order holds and the gaps widen

Supabase Pro comes to $2,950 a month at a million users: the Pro fee plus 900,000 users above the included 100,000 at $0.00325 each. Firebase comes to $4,415: $275 for users 50,001 to 100,000 and $4,140 for the next 900,000 at $0.0046 each. Clerk comes to $17,225 read band by band, which is the Pro fee plus $1,000 for the 50,000 users in the $0.02 band and $16,200 for the 900,000 in the $0.018 band. Clerk's table does not say whether a band's rate covers every user or only the users inside it. Under the other reading the figure is $17,125. Auth0 Enterprise is a sales quote, so there is no published figure at a million users.

The features that move the bill

Yearly billing on Auth0 charges 11 months. Essentials at 500 users comes to $385 a year on the annual toggle. Auth0 also keeps MFA factors off its Free plan, so an app that needs a second factor is on Essentials from the start.

Firebase charges extra for enterprise sign-in. SAML and OIDC are free up to 50 users per project, then $0.015 per user on Google's table. Phone sign-in and MFA are billed per SMS, separately from the user count, so a volume of text messages can outrun the user line.

Supabase's $10 credit covers compute only. It pays for one Micro instance, so every extra project is billed on top of the Pro fee, from $10 a month each.

Which to pick, by user count

With no MFA, a free tier works up to 50,000 users on three of the four vendors, and Auth0's free plan ends at 25,000. Choose by the limits you can live with: Supabase Free pauses after a week, and Clerk Hobby stops at three seats. The Vercel review covers the hosting side of the same app. For a team that needs MFA, Clerk Pro includes it in a flat monthly fee, while Firebase bills it per text message.

Already paying for Supabase at 100,000 users, Pro is the cheapest login line, because the database is on the same invoice. Among standalone services at 100,000 users, Firebase Identity Platform is the lowest. The Firebase versus Supabase comparison covers when the database choice matters more than the login price. Teams that want Postgres without Supabase can compare hosts in the Postgres hosting list and read the Neon review.

Auth0's list rate implies about $7,000 a month at 100,000 users on Essentials, so ask for a written quote before you assume that figure. For the wider set of backend platforms, the backend-as-a-service roundup and the serverless platforms list show the alternatives.

How we checked these prices

Louis Corneloup, founder of Dupple and Toolradar, wrote this comparison. The prices come from the pricing pages of Clerk, Auth0, Supabase and Firebase, plus the Identity Platform pricing table, all read on October 10, 2026. Figures built from a vendor's per-user rate multiplied by the volume are our arithmetic, not a published total. Each vendor's product record is on Toolradar: Clerk, Auth0, Supabase and Firebase.

FAQ

How much does Auth0 cost in 2026?

Auth0's Free plan is free for up to 25,000 monthly active users and needs no card. Essentials starts at $35 a month for up to 500 users, and Professional starts at $240 a month for up to 500. Above the calculator's 30,000+ step, Auth0 routes you to sales, and yearly billing charges 11 months.

Is Auth0 free for 10,000 users?

Yes. The Free plan covers up to 25,000 monthly active users at $0. It does not include MFA factors, which start on Essentials.

Is Clerk cheaper than Auth0?

At 10,000 users both are free on their entry plans, and Clerk Pro is the cheaper MFA option. At 100,000 users, Clerk costs far less than the roughly $7,000 a month that Auth0's Essentials implies. That figure is our arithmetic, not a quote.

What is the cheapest authentication service for 100,000 users?

If you already run Supabase, Pro is the cheapest login line, because the plan covers 100,000 users. Among standalone services, Firebase Identity Platform at $275 a month is the lowest. Clerk costs more.

Is Firebase authentication free?

It is free up to 50,000 monthly active users with Identity Platform. Above that, Google's table charges $0.0055 per user from 50,001 to 100,000, and phone sign-in and MFA are billed per SMS. SAML and OIDC sign-in is free for the first 50 users per project.

Does Supabase charge per user for auth?

Yes, by monthly active user. Free includes 50,000 users, and Pro includes 100,000 in its monthly fee, then $0.00325 for each user above that. A free project pauses after a week without activity, and only two projects can be active.

How much does Clerk cost for 100,000 users?

It costs $1,025 a month on monthly billing: the Pro fee plus $1,000 for the 50,000 users above the included 50,000 at $0.02 each. Annual billing lowers the base fee to $20, for $1,020. Clerk bills retained users, which can differ from monthly active users, so count yours before you compare.

Cite this: Devshot, "Authentication Pricing Compared (2026): Clerk vs Auth0 vs Supabase Auth vs Firebase", October 2026, with prices read on October 10, 2026.

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