Auth21 Kernel | Docs

Google integration docs

Setup guidance for Google Login and Workspace-oriented OAuth: scopes, PKCE, callback validation and fast troubleshooting.

Google onboarding guide

Optimize for speed, clarity and clean browser flows

Google should feel easy to adopt. Auth21 adds discipline around PKCE, callback validation and operational clarity without making the setup feel heavy.

Provider setup

Keep the initial configuration tight

Configure explicit callback URLs from the start.
Keep consent and scopes aligned to product need.
Use PKCE by default for browser-facing login flows.

Adoption goal

Move fast without making callback bugs look normal

Google can feel forgiving in early testing, but exact callback and scope discipline are what keep onboarding fast at scale.

Scopes and consent

Minimal

Start with the minimum

Ask only for the scopes required by the actual product experience.

Readable

Explain consent clearly

Make sure product copy and Google consent intent match what users see in the flow.

Practical

Do not over-spec

Extra scopes add friction and confusion faster than they add real value during onboarding.

PKCE-first browser flow

Recommended path

User
    ->
Auth21 /authorize
    ->
Google login
    ->
Callback validation
    ->
Token exchange with PKCE

Why this matters

Google adoption feels modern when the browser flow is clean, predictable and protected. PKCE should not be treated like an optional afterthought.

Callback validation

Strictness wins

Exact redirect URI or fail fast

Treat redirect mismatch as an integration bug, not as "close enough" setup. The right behavior is clean failure, not permissive routing.

Fast debugging

Check redirect URI first.
Validate PKCE verifier pairing.
Review scopes and consent assumptions.
Inspect traces before changing code blindly.

Troubleshooting

Common failures

Invalid redirect URI
PKCE verifier mismatch
Scope misconfiguration
Consent screen or client setup issues

Mindset

In Google flows, the best operational win is reducing ambiguity. If onboarding is clean, support volume drops fast.