Clerk vs Auth0

At a glance

1. Clerk and Auth0 count different people

Read the unit before the price. Each vendor defines it in its own words:

Clerk counts the first day free. A signup that never returns is excluded from MRU, but counts toward MAU if non-internal and authenticated.

A consumer app with heavy sign-up churn will look cheap on Clerk, and part of that cheapness is definitional.

Vendor pricing pages, checked on 10 November 2026: Clerk Hobby includes 50,000 MRU per app for $0; Auth0 Free includes 25,000 MAU for $0.

2. Who should not pick Auth0's paid B2C plans

• Clerk forbids a limitless free tier: Hobby stops at 50,000 MRU per app with no MFA or passkeys, and one month of grace before the app stops working.
• Clerk forbids big free organisations: 100 MRO per app, 20 members each. An MRO has at least 2 members, one of them an MRU that month.
• Auth0 forbids paying for exactly what you use. Between tiers you are billed at the next tier up.
• Avoid Auth0 B2C Essentials and Professional if you need enterprise connections: both list them as "not available". Free includes 1; custom SSO tiers require Enterprise.

3. On Auth0, the 501st user costs $35

Auth0's B2C price is a staircase. You pay for the tier you land in:

At 500 MAU, Essentials is $35 / 500 = $0.07 per user. User 501 moves you to the 1,000 tier: $70 − $35 = $35 for one person. The $70 bill is double $35.

The usage punished is a spike that crosses a boundary. One launch week past a tier line bills the whole next tier. Professional has a harder cliff: $240 climbing to $3,200, then no self-serve price at all. Professional's printed prices end at 20,000 MAU for B2C and 10,000 for B2B.

Annual billing keeps the steps: yearly is 11 × monthly, so 50,000 MAU on Essentials is 11 × $3,500 = $38,500.

4. Who should not pick Clerk without budgeting add-ons

Clerk Pro is $25/month, or $20/month billed annually. It includes 50,000 MRU per app, then $0.02 per MRU with volume discounts. Every plan allows unlimited applications.

The add-ons move the bill:

Ten enterprise customers, one SSO connection each, cost (10 − 1) × $75 = $675/month. From January 2027, Directory Sync for the same ten adds another (10 − 1) × $75 = $675.

Protect at 200,000 checks is (200,000 − 10,000) × $0.002 = $380.

Avoid Clerk's self-serve plans if you need a 99.99% SLA or a HIPAA BAA; both are Enterprise-only.

5. The 140x gap is correct arithmetic on two different quantities

Paid-plan estimates at equal numeric inputs, not an identical population. Auth0 counts MAU; Clerk counts MRU.

TIERS = [(500, 35), (1_000, 70), (2_500, 175), (5_000, 350), (7_500, 525),
         (10_000, 700), (20_000, 1_400), (30_000, 2_100), (40_000, 2_800), (50_000, 3_500)]

def auth0(mau):  # between tiers you pay the next tier up
    return next((p for cap, p in TIERS if mau <= cap), None)  # breaks: >50,000 unpriced

def clerk_pro(mru):  # ignores Clerk's volume discounts
    return 25 + max(0, mru - 50_000) * 0.02

for n in (501, 50_000, 100_000):
    print(n, auth0(n), clerk_pro(n))

At 50,000 non-internal MAU per tenant/month, Auth0 is $3,500; at 50,000 later-day MRU per app, Clerk is $25 + 0 × $0.02 = $25. $3,500 / $25 = 140. 140x prices 50,000 people who logged in against 50,000 who came back on a later day. Not the same crowd.

At 100,000 MRU, Clerk is 50,000 × $0.02 + $25 = $1,025/month. Auth0's B2C sheet ends at 50,000: "contact us".

6. Pick by who you are billed for, then check the next boundary

Choose Clerk Pro if you need MFA, passkeys or branding removal below 50,000 MRU per app; Hobby excludes them.

For 10 dashboard seats, 5,000 MRU and 200 qualifying MRO, Clerk Business costs $300 + $100 + (200 − 100) × $1 = $500/month. Auth0 B2B Essentials is $1,300 at 5,000 MAU, but Essentials and Professional allow only 10 organisations, not 200.

Choose Auth0 Professional if you need custom database connections or cross-app SSO; it includes 12 tenants.

Check today:

1. Price distinct non-internal MAU per Auth0 tenant and later-day MRU per Clerk app, with required plans and add-ons.
2. Find your Auth0 tier and how many MAU separate you from the next one.
3. List SSO and Directory Sync connections you will run on 1 January 2027.

Cost arithmetic at volume

These are computed from the published unit prices, not measured. Each row prints its own formula, so you can replace our assumption with your traffic and redo it.

Decision matrix

Rows are the situation you are actually in. Pick the row before you read the pricing page again.

Code and configuration

// Clerk bills a retained user, not a session: the first day is free.
const { totalCount } = await clerkClient.users.getUserList({ limit: 1 });
// Here it breaks: past 50,000 MRU on Pro each extra user is $0.02/month,
// and Hobby gives one grace month before requests stop being served.
if (totalCount > 50_000) console.warn(totalCount, "MRU — check the plan");

# Auth0 prices the tier, not the user: 501 MAU bills as 1,000.
TIERS = [(500, 35), (1_000, 70), (2_500, 175), (5_000, 350)]
def essentials(mau):
    return next(p for cap, p in TIERS if mau <= cap)
print(essentials(501))  # 70, not 35
# Here it breaks: above 50,000 B2C MAU the printed sheet ends.

What you gain, what you give up

Migration path

Common questions

Sources & verification

Prices and limits were read from these pages on 2026-11-10. Vendor marketing claims are quoted as claims. Anything derived is arithmetic on the numbers below.

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