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Auth pricing at 100K users (2026)

What auth really costs once your app reaches 100,000 monthly users, from $0 to about $4,700 a month on list prices. WorkOS, Better Auth, Auth.js, Supabase Auth, Firebase Authentication, Clerk, Kinde, Descope, Auth0 and Stytch compared on free limits, cost at 100K, the price of each extra 10,000 users, and how each one counts a user. Ordered from cheapest to most expensive at 100,000 users, with quote-only pricing last; prices re-checked on official pricing pages on Oct 25, 2026.

Editorial picks for this use case. See each tool page for its score breakdown. Last updated 2026-10-25.

The short answer

At 100,000 monthly users, hosted auth ranges from $0 (WorkOS AuthKit) to about $4,700 a month (Descope Pro), and some providers only quote that volume through sales. Supabase Auth is $25/mo on Supabase Pro, Firebase Authentication with Identity Platform is about $275/mo, Clerk Pro is about $1,025/mo and Kinde is about $1,530 to $1,600/mo depending on plan. Open-source libraries (Better Auth, Auth.js) have no per-user fee at all because the users live in your own database. Every number below comes from the provider’s own pricing page, re-checked on October 25, 2026, and assumes list prices, no startup discounts and no add-ons.

Cost at 100,000 users, side by side

ProviderFree plan coversMonthly cost at 100K usersEach extra 10K users above 100K
WorkOS AuthKit1,000,000 MAU$0$0 up to 1M, then $2,500 per extra 1M
Better AuthNo user limit (MIT library)$0 per user$0 (optional Infrastructure Pro is $20/mo flat)
Auth.jsNo user limit (open source)$0 per user$0
Supabase Auth50,000 MAU$25 (Pro plan, 100,000 MAU included)$32.50 ($0.00325 per MAU)
Firebase Auth + Identity Platform50,000 MAUabout $275 (50,000 × $0.0055)$46 ($0.0046 per MAU from 100K to 1M)
Clerk50,000 retained users per appabout $1,025 (Pro $25 + 50,000 × $0.02); $1,020 billed annually$180 ($0.018 per retained user from 100K to 1M)
Kinde10,500 MAUabout $1,534 on Plus ($75 + 89,500 × $0.0163); $1,591 on Pro; $1,601 on Scale$163 on Plus, $175 on Pro, $151 on Scale
Descope7,500 MAU (hard limit)about $4,549 on Growth ($799 + 75,000 × $0.05); $4,749 on Pro; both billed annually$500 ($0.05 per MAU)
Auth025,000 MAUSales quote (self-serve calculator stops at 30,000+)Not published
Stytch10,000 MAUUsage-based; per-MAU rate shown only in its calculatorNot quoted here

Auth only. Hosting, database, SMS and email costs are extra on every option. Prices checked Oct 25, 2026 on each provider’s pricing page (sources below).

How each one counts a “user”

The providers don’t count the same thing. WorkOS counts anyone who signs up, signs in or updates a profile in a calendar month. Clerk counts monthly retained users: someone who comes back at least a day after signing up, so one-time sign-ups are never billed. Kinde does not count users on paid subscriptions you bill through Kinde (customers paying more than $4/month), so a paid SaaS can pay far less than the table shows. Supabase, Firebase, Descope and Auth0 count monthly active users. An app with 100,000 sign-ups but 40,000 returning users could stay on Clerk’s free Hobby plan, so check your own retention before comparing.

The cheap options and their catches

WorkOS is free for user management up to 1 million MAU, but enterprise SSO and directory sync are $125 per connection a month (1 to 15), and a custom domain is $99/mo. Supabase Auth is cheap because it is bundled with a Supabase project: the $25 Pro plan includes $10 of compute credits (one Micro instance), and phone MFA ($75/mo for the first project) and SAML SSO (50 SSO users included, then $0.015 each) are extra. Firebase charges the per-MAU rate once you upgrade to Firebase Authentication with Identity Platform, and phone sign-in is billed per SMS on the Blaze plan. Better Auth and Auth.js are free code you run yourself, so you own security patches, email delivery and uptime; Better Auth’s optional Infrastructure adds a dashboard, audit logs and bot detection from $0 (Starter) or $20/mo (Pro).

The pricier options and why teams still pick them

Clerk costs more per user but ships the most polished prebuilt React and Next.js components, and Pro includes 1 SSO connection and 1 directory sync connection per app. Kinde bundles auth with subscription billing (0.5% to 0.7% per transaction), feature flags and organizations, and its Plus plan ($75/mo) includes unlimited enterprise SSO at no extra cost, which makes Plus cheaper than Pro at 100,000 users thanks to its lower per-MAU rate. Descope sells a visual flow builder and agent/MCP auth, with plans billed annually. Auth0 leads on enterprise and compliance features from Okta, but at this volume you negotiate with sales.

Which to pick at 100,000 users

If you want the lowest bill with hosted auth: WorkOS ($0 until 1M users) or Supabase Auth ($25 if Supabase is already your backend). If you want zero per-user cost and users in your own database: Better Auth. If your users are mostly paying subscribers: run Kinde’s numbers, since billed users are free. If speed of setup and UI polish matter more than about $1,000 a month: Clerk. Whatever you pick, model 2× and 5× your current users before you commit, because the gap widens: at 200,000 users Clerk Pro is about $2,825/mo and Supabase Pro about $350/mo, while WorkOS stays at $0.

The providers, cheapest first

#1
W
WorkOS
Enterprise-ready auth and SSO
Verified
78
/ 100
 #2
B
Better Auth open source
Open-source TypeScript auth framework
Verified
86
/ 100
 #3
A
Auth.js (NextAuth.js) open source
The classic open-source auth library for Next.js, now part of Better Auth
Verified
73
/ 100
 #4
S
Supabase Auth open source
Auth built into your Supabase Postgres, with 50,000 free MAU
Verified
85
/ 100
 #5
F
Firebase Authentication
Google's drop-in auth for web and mobile apps
Verified
74
/ 100
 #6
C
Clerk
User management and authentication
Verified
87
/ 100
 #7
K
Kinde
Auth, B2B organizations and billing in one, with 10,500 free MAU
Verified
76
/ 100
 #8
D
Descope
Drag-and-drop auth flows, plus MCP and AI-agent auth
Verified
70
/ 100
 #9
A
Auth0
Identity platform by Okta
Verified
70
/ 100
 #10
S
Stytch
Authentication and fraud prevention
Verified
68
/ 100

Side-by-side comparison

ToolScoreFree tierPricingBest for
WorkOS78Yes: AuthKit free up to 1M MAUSSO/Directory Sync $125/connection/mo (volume discounts)SaaS that will sell to enterprises needing SSO/SCIM
Better Auth86Yes: MIT library free to self-host; Infrastructure Starter $0Library free; optional Infrastructure Pro $20/moOwning auth in your own database with no per-user fees
Auth.js (NextAuth.js)73Yes: fully free and open source, no per-user feesFree (ISC open source); you host it and pay only for your own databaseExisting Next.js apps already on next-auth; new projects should look at Better Auth first
Supabase Auth85Yes: 50,000 monthly active users on the Supabase Free plan (free projects pause after 1 week of inactivity, 2 active projects max)Included in Supabase plans: Free $0 (50,000 MAU); Pro from $25/mo (100,000 MAU, then $0.00325 per MAU); Team from $599/mo; Enterprise custom. Advanced phone MFA, SAML SSO and leaked-password protection are paid featuresApps already on Supabase, or vibe-coded apps from Lovable and Bolt that need sign-in tied to row-level security
Firebase Authentication74Yes: no-cost on the Spark plan; with Identity Platform free up to 50K MAU (Spark caps Identity Platform at 3,000 daily active users, and password-reset emails at 150/day)No-cost Spark plan; with Identity Platform, no-cost up to 50K MAU (50 MAU for SAML/OIDC), then Google Cloud pricing; phone verification SMS is Blaze (pay-as-you-go) only and billed per SMSMobile and Flutter apps, or projects already on Firebase and Google Cloud
Clerk87Yes: 50,000 monthly retained users per appPro $25/mo ($20 annual), then $0.02/MRU over 50KThe fastest auth for Next.js/React SaaS
Kinde76Yes: 10,500 MAU free forever, no credit card, including social login, MFA, organizations and custom domainFree $0 (10,500 MAU); Pro $25/mo (10,500 MAU included, then $0.0175 per extra MAU); Plus $75/mo (free enterprise SSO); Scale $250/mo; billing customers through Kinde adds 0.5–0.7% per transaction (0.7% Free/Pro, 0.6% Plus, 0.5% Scale), and those billed users' MAU is freeSaaS founders who want auth, orgs and subscription billing from one provider
Descope70Yes: 7,500 MAU, 10 tenants and 3 SSO connections free forever, no overages (upgrade required past limits)Free Forever $0 (7,500 MAU, 10 tenants, 3 SSO connections, hard limits); Pro from $249/mo billed annually (10,000 MAU, then $0.05/MAU); Growth from $799/mo (25,000 MAU); Enterprise customB2B apps and MCP servers that need tenant SSO or agent auth without writing flows by hand
Auth070Yes: up to 25,000 MAUEssentials from $35/mo (B2C, 500 MAU) or $150/mo (B2B)Enterprise identity requirements and compliance
Stytch68Yes: 10,000 MAU, 5 SSO/SCIM connectionsUsage-based above free allowance; SSO/SCIM $125/connectionPasswordless and fraud-aware auth

FAQ

Is WorkOS free?
WorkOS free tier: Yes: AuthKit free up to 1M MAU. Paid pricing: SSO/Directory Sync $125/connection/mo (volume discounts).
Is Better Auth free?
Better Auth free tier: Yes: MIT library free to self-host; Infrastructure Starter $0. Paid pricing: Library free; optional Infrastructure Pro $20/mo.
Is Auth.js (NextAuth.js) free?
Auth.js (NextAuth.js) free tier: Yes: fully free and open source, no per-user fees. Paid pricing: Free (ISC open source); you host it and pay only for your own database.
How are these tools ranked?
Each tool is scored out of 100 on fit, vibe-coder friendliness, output quality, pricing, ecosystem, momentum and code ownership, using desk research of official docs and pricing pages. Affiliate status never affects scores.
What is the cheapest auth at 100,000 monthly active users?
WorkOS AuthKit, which is free up to 1 million monthly active users. Among hosted options bundled with a database, Supabase Auth on the $25/mo Pro plan includes 100,000 MAU. Better Auth and Auth.js have no per-user fees because you host them.
How much does Clerk cost for 100,000 users?
About $1,025/mo billed monthly: Pro is $25/mo with 50,000 monthly retained users included, then $0.02 for each retained user from 50,001 to 100,000. Billed annually it is about $1,020/mo. Users who sign up and never return after the first day are not counted.
How much does Firebase Authentication cost at 100,000 users?
With Identity Platform, the first 50,000 MAU are free and the next 50,000 cost $0.0055 each, so about $275/mo. Phone sign-in is billed per SMS on top.
How much does Kinde cost for 100,000 users?
About $1,534/mo on Plus ($75 + 89,500 extra MAU × $0.0163), $1,591 on Pro ($25 + 89,500 × $0.0175) and $1,601 on Scale ($250 + 89,500 × $0.0151). Users paying you more than $4/month through Kinde billing don’t count toward MAU.
How much does Auth0 cost at 100,000 MAU?
Auth0 doesn’t publish a self-serve price at that volume. Its free plan covers 25,000 MAU and its pricing calculator stops at 30,000+, above which you talk to sales.

Sources (checked Oct 25, 2026)

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