Auth0 vs Clerk vs Firebase Authentication

Side by side

Auth0 vs Clerk vs Firebase Authentication: value, access facts, plan limits and bottom lines

Metric	Auth0	Clerk	Firebase Authentication
What you're paying for	Compliance includedAudited enterprise identity — SOC 2 Type 2, ISO 27001 and six hosting regions — with a free plan of 25,000 users and one enterprise connection.	Saves engineering timeReady-made sign-in and user management, free for 50,000 retained users, with SSO and MFA from $25 a month at published prices.	Worth the priceSign-in that plugs into Firebase and Google Cloud, free to 50,000 monthly users, with SAML at $0.015 per user and a self-serve Google Cloud BAA.
Overall score	6.8	8.2	8.4Best
Free option	Free plan	Free plan	Free plan
Card to start	No card needed	No card needed	No card needed
Getting access	Self-serve	Self-serve	Self-serve
Starter priceCheapest paid plan	$35/mo	$25/mo	$0.0055/MAU above 50,000
Pricing model	Tiered	Usage-based	Usage-based
Pricing page	Public prices	Public prices	Public prices
Free plan	25,000 MAU, no card to sign up	50,000 MRU per app, no card	50,000 MAU; Spark capped at 3,000 a day
Entry paid plan at 10,000 users	$700/mo (B2C Essentials)	$25/mo (Pro), $20 billed annually	$0 (Blaze), 50,000 MAU at no cost
Enterprise SSO	1 connection free; 3 on B2B Essentials, more from $100/mo each	1 connection on Pro, then $75/mo each	50 SAML/OIDC users free on Blaze, then $0.015 each
SOC 2 report	Type 2, from the Support Center	Type 2, on Business ($300/mo)	SOC 2 (Google), via Compliance Reports Manager
HIPAA BAA	With an Enterprise subscription	Enterprise plan	Google Cloud BAA, accepted in the console
Data region	AU, CA, EU, JP, UK or US per tenant	US only	US only
Log retention on the entry paid plan	5 days (Essentials)	7 days of application logs (Pro)	30 days in Cloud Logging (activity logs, opt-in)
Bottom line	From its public pages, Auth0 is the most complete compliance and data-region package of the three, with a generous free plan. Its paid plans cost more per user than the others, so price the B2C or B2B plan at your user count first.	From its public pages, Clerk offers the largest free allowance here and clear prices from the first user to SSO. Check US-only hosting and the plan that unlocks the SOC 2 report against your customers’ requirements.	From its public pages, Firebase Authentication is the least expensive route here to SAML SSO and a self-serve BAA, inside the Firebase platform. Check US-only processing and the protections it does not list.

Evidence: Auth0: facts checked 2026-10-15 from its public sign-up and pricing pages, no completed hands-on run; Clerk: facts checked 2026-10-15 from its public sign-up and pricing pages, no completed hands-on run; Firebase Authentication: facts checked 2026-10-15 from its public sign-up and pricing pages, no completed hands-on run. Prices in USD as listed, excluding tax. "–" means not recorded.

When to pick each

In the words of each review, with the date its facts were checked.

Entry price

Baseline: each product's cheapest paid plan, per month. Included usage differs, so read the line under each price.

Which one fits

If you need to start today without a sales call

Firebase AuthenticationSelf-serve sign-up, no card needed; the highest score of the 3 self-serve products here (8.4/10).

If you want to try it without entering a card

Firebase AuthenticationFree plan, no card needed, and the highest score of the 3 that skip the card (8.4/10).

Lowest starter price

Clerk$25/mo for the Pro plan. Firebase Authentication lists no comparable paid price.

Highest overall score

Firebase Authentication8.4/10 (Excellent). The review shows the score breakdown and the run behind it.

Picked by fixed rules from the table above, not by hand. How we score

Full reviews

• Auth0 review: plans, prices and access facts
• Clerk review: plans, prices and access facts
• Firebase Authentication review: plans, prices and access facts