External-first evidence · near-real-time source measurements and periodic public benchmarks. AI Fast Now direct measurements are historical; paid emergency verification is OFF by default.
Anthropic · Deprecated models
Claude Sonnet 4.5
Anthropic deprecated this Sonnet snapshot on September 30, 2026 and names Sonnet 5.5 as its replacement.
Independent external model-route observations
Checking verified public snapshots. Participation alone does not establish fresh performance.
Official API model IDclaude-sonnet-4-5-20250929
Release channelstable · deprecated
Deprecated2026-09-30
Scheduled retirement2026-11-30
ReplacementClaude Sonnet 5.5
Retirement scheduled: 2026-11-30 Official facts verified 2026-10-02.
01
Model identity and lifecycle
Family: Claude. Generation: 4.5. This is a previous generation; it is preserved separately from the current lineup. The catalog uses the API identifier shown above.
02
How to interpret performance
This model is assigned to ongoing independent API measurements. External source cycles and comparable workload cadences remain separate. Normal paid direct measurements are on emergency standby. Sampling cadence and request settings remain explicit. Measurements are comparable only when model revision, region, profile, prompt version, reasoning, output limit and cache policy match. Missing data never means a provider outage.
Claude consumer app performance may differ from direct API observations. No score, throughput estimate or best-time prediction is inferred from official specifications.
03
Official evidence
Anthropic model documentation · Verified 2026-10-02. Availability and lifecycle can change; the documented source governs the API contract.
