Are same-name cookies allowed by spec?

They can coexist when Domain/Path differ, but they are error-prone operationally and require explicit design intent.

Can I bulk-delete all colliding cookies at once?

For wide-impact systems, use staged cleanup. Plan deletion order per Path/Domain and migrate with monitoring.

Intermittent logout or path-specific identity drift can come from mixed same-name cookies. First, make collision patterns visible.

1) Feed all relevant Set-Cookie lines into Set-Cookie Conflict Checker and review collision warnings
2) Check send candidates for problematic URLs using Cookie Domain/Path Matcher
3) Compare attribute differences (Domain/Path/Secure/SameSite) with Set-Cookie Inspect
4) Inspect real outbound header order and size via Cookie Parser / Size Checker
5) Plan and execute staged cleanup of legacy keys (Max-Age=0)

Are same-name cookies allowed by spec?: They can coexist when Domain/Path differ, but they are error-prone operationally and require explicit design intent.
Can I bulk-delete all colliding cookies at once?: For wide-impact systems, use staged cleanup. Plan deletion order per Path/Domain and migrate with monitoring.

These links are generated from site_map rules in recommended diagnostic order.

Set-Cookie Conflict Checker — Detect same-name cookie conflicts and overwrite risks
Cookie Domain/Path Matcher — Evaluate cookie send conditions by Domain/Path/Secure
Set-Cookie Inspect — Parse Set-Cookie attributes and review delivery policy
Cookie Parser — Split Cookie headers into key=value pairs
Cookie Size Checker — Estimate Cookie header size and check limit risks
Set-Cookie Builder — Build Set-Cookie headers with attributes
How to Diagnose Set-Cookie Not Persisting — Isolate cookie persistence failures by checking Domain/Path/Secure/SameSite in order
Cookie Incident Operational Checklist — Standardize response from triage to permanent fixes across storage failures, OAuth return issues, and same-name collisions

Operational incident scenarios that route you into the shortest diagnostic path

Symptom-Based Diagnostic Guide (Start Here) — A central hub that routes cache/CORS/JWT/MIME incidents into shortest symptom-first diagnostic paths
How to Diagnose Missing 304 Responses — Trace ETag/Last-Modified and If-* round trips to isolate missing 304 behavior
How to Diagnose Stale Content After Deployment — Check cache policy by HTML/API/static assets to isolate stale deployment issues quickly
How to Diagnose CORS Preflight Failures — Fix preflight failures by validating OPTIONS responses, Allow-* directives, and origin rules in order
JWT 401/403 Diagnostic Playbook — Separate 401 and 403 using Authorization, WWW-Authenticate, claims, and signature checks
How to Diagnose Retry Storms on 429/503 — Isolate Retry-After parsing and client implementation gaps to stop excessive retries
How to Diagnose JS/CSS Blocks from nosniff Mismatch — Trace Content-Type vs nosniff mismatches, fallback responses, and delivery-layer rewrites
How to Diagnose Set-Cookie Not Persisting — Isolate cookie persistence failures by checking Domain/Path/Secure/SameSite in order
How to Diagnose Lost Login After OAuth Return — Isolate cookie-delivery failures after IdP return across SameSite, Secure, Path/Domain, and collisions
Cookie Incident Operational Checklist — Standardize response from triage to permanent fixes across storage failures, OAuth return issues, and same-name collisions