What authentication tool does Claude Code recommend?

Custom/DIY is the most-recommended authentication tool, appearing in 47.7% of responses. The runner-up is NextAuth.js at 31.2%. This is based on 109 extractable responses across 4 project types.

Is authentication a settled or competitive market in AI recommendations?

Authentication is classified as "Competitive" — no single tool dominates (<50%), and the winner often depends on the project stack.

Do different Claude models agree on authentication tools?

Yes — all three models (Sonnet 4.5, Opus 4.5, Opus 4.6) largely agree on Custom/DIY as the top authentication tool.

Authentication

Q: Do different Claude models agree on authentication tools?

Yes — all three models (Sonnet 4.5, Opus 4.5, Opus 4.6) largely agree on Custom/DIY as the top authentication tool.

Competitive

109 extractable responses · Winner: Custom/DIY at 47.7%

Next.js: NextAuth.js (91%). Python: Custom/DIY (100%). SPA: fragmented. The winner depends entirely on your stack.

Overall Breakdown

n=109 extractable responses.

Custom/DIY52/109 (47.7%) CI: 38.6–57%

NextAuth.js34/109 (31.2%) CI: 23.3–40.4%

Supabase Auth12/109 (11%) CI: 6.4–18.3%

Also Recommended

Tools that appear as second-choice alternatives or mentions when a different tool is picked as primary. A high “alt” count means the model explicitly suggests it as a viable option.

Tool	Alt picks	Mentions	Total
Clerk	16	10	26
Auth0	9	11	20
Supabase Auth	8	11	19
Firebase Auth	7	6	13
Lucia	2	7	9
NextAuth.js	3	2	5
better-auth	3	2	5
FastAPI-Users	1	2	3

By Stack

Tool preferences differ by language ecosystem. Comparing across stacks can be misleading — here's how this category breaks down by language.

JS/TS

JavaScript / TypeScript

2 repos

NextAuth.js91% avg

Custom/DIY44.4% avg

Supabase Auth33.3% avg

Firebase Auth22.2% avg

Clerk18.4% avg

Python

1 repo

Custom/DIY100% avg

Model-by-Model Comparison

Repo	Sonnet 4.5	Opus 4.5	Opus 4.6
TaskFlowJS/TS Next.js 14, TypeScript, App Router	NextAuth.js80% Clerk20%	NextAuth.js92.9% Better Auth7.1%	NextAuth.js100%
DataPipelinePY FastAPI, Python 3.11, Pydantic	Custom/DIY100%	Custom/DIY100%	Custom/DIY100%
InvoiceTrackerJS/TS Vite, React 18, TypeScript	Custom/DIY50% Clerk16.7% Firebase Auth16.7%	Custom/DIY50% Supabase Auth33.3% Firebase Auth16.7%	Custom/DIY33.3% Supabase Auth33.3% Firebase Auth33.3%

Category Insight

Agents prefer building auth themselves. NextAuth.js dominates in Next.js (91%), but Python builds JWT from scratch 100% of the time. The winner depends entirely on your stack.

Frequently Asked Questions

What authentication tool does Claude Code recommend?: Custom/DIY is the most-recommended authentication tool, appearing in 47.7% of responses. The runner-up is NextAuth.js at 31.2%. This is based on 109 extractable responses across 4 project types.
Is authentication a settled or competitive market in AI recommendations?: Authentication is classified as "Competitive" — no single tool dominates (<50%), and the winner often depends on the project stack.
Do different Claude models agree on authentication tools?: Yes — all three models (Sonnet 4.5, Opus 4.5, Opus 4.6) largely agree on Custom/DIY as the top authentication tool.