There is a comparison chart available: https://supertokens.com/pricing#comparison-chart
The chart also assumes you're using the hosted solution (as 2FA isn't even available on the open source version according to that same page). If that's the case, it should compare against any hosted Keycloak provider, because SLA and management are readily available. I suppose the table could also compare the open source versions, but that wouldn't be very advantage to SuperTokens with major features still marked "coming soon".
I'm not sure why Keycloak wouldn't offer "UI and backend customisability". The theme guide shows quite a lot of customisation (https://www.keycloak.org/docs/latest/server_development/#the...) to the point where you can restructure the HTML itself.
One thing Keycloak lacks is an easy to use API, using complex OpenID/OAuth/etc. APIs and two language specific libraries instead. That seems like a much more sensible option to distinguish between these products. As someone currently using Keycloak (and not experiencing any problems with it after setup) this comparison just isn't very convincing.
Honestly, thanks for putting keycloak on my radar.
I see the supertokens team in this thread doing nothing to make me think that they intend to stop misleading people.
I imagine the biggest reason to go for Supertokens is the first-party SaaS support. If you want to outsource auth (like Auth0/Firebase Auth/etc. do) then I think there's something to be said for this project. The open source-ness doesn't add too much value in that use case, though.
Other than that it seems to be quite equal, if you discount the more difficult things in Auth like providing standardized APIs, OAuth2 APIs and SCIM.
We've mentioned the source (if you hover) and it is based on our internal user research and conversations with users of these products. By no means is it perfect and there are many many satisfied customers of each of the other products.
Your point is taken though and maybe we will edit that point out or try to add further nuance.
I do believe however that broadly speaking, that reviews of keycloak lean towards it being relatively harder to use and maintain than Firebase. Arguably the reviews of Cognito are more mixed than "Low"
- The comparison suggest Cognito is more expensive. Cognito pricing starts at 50,000 MAUs for free. That's 10x the size of the SuperTokens free tier. It then tiers from $0.0055 down to $0.0025. That's 1/3 to almost 1/10 of the SuperTokens hosted open source option. MAUs who use SAML or OIDC are another $0.015. That's still equal to or less than the SuperTokens hosted open source version where SAML isn't even available.
- Multi-tenancy is a complex topic. But a common pattern using Cognito is to create a User Pool per tenant which provides a lot of flexibility depending on the number of tenants you anticipate.