Claude 3 Sonnet was released with Claude 3 Opus on March 4, 2024. Its defining position was the middle of a three-model family, balancing cost, speed and capability. The dated identifier `claude-3-sonnet-20240229` must not be conflated with any subsequent “Sonnet 3.5,” “3.7” or “4” release.
Historical research cutoff: 25 October 2026. Primary-source historical claims are date-scoped; cloud entitlements, region-specific availability, current pricing and rate limits are not implied.
Release identity at a glance
- Provider
- Anthropic
- Model family
- Claude 3 Sonnet
- Public launch
- 2024-03-04
- API ID / checkpoint
- claude-3-sonnet-20240229
- API retirement status
- 2025-07-21
The release and why it mattered
Anthropic presented Claude 3 as its next generation with improved multimodal image understanding and international availability. At the family launch, Opus and Sonnet were available while Haiku was still planned. That sequencing is important: a family announcement is not a simultaneous ship date for each variant.
Capabilities and genuine use cases
For an API consumer, a middle-tier model can be appropriate for passage extraction, drafting and high-frequency questions. But recognizing text in a photograph or processing a chart is not equivalent to verifiable numerical extraction. Check the exact dated snapshot and whether image support was available at the chosen endpoint before writing a compatibility assertion.
Integration and version identity
Existing systems should log the `claude-3-sonnet-20240229` ID, document parser behavior and structured outputs enforced outside the model. Anthropic’s retirement table assigns July 21, 2025 to this identifier. That date applies to Anthropic-operated services; AWS and Google-operated offerings may use different shutdown schedules.
Limits and evidence gaps
Family benchmark claims are not identical to a task-level evaluation of Sonnet and cannot be projected onto other Sonnet generations. Context, latency and paid availability should be treated as separately verified fields. The model’s retirement makes a 2024 plan comparison unsuitable for today’s buyers.
How to choose or migrate
Select this archive entry when analyzing which parts of an old Claude 3 integration require migration. New deployments should choose a supported snapshot and measure response format compliance, factual extraction errors and total operational cost.
Reproducible evaluation checklist
For older Claude services, compare the vendor-operated API lifecycle with the lifecycle published by the actual cloud partner. Exercise long inputs, structured outputs and tool argument validation as separate acceptance tests. Do not assume that matching family names imply identical backend checkpoints.
Collect the exact Messages API version, system instructions and model string from a reproducible request. An active cloud model and a retired direct-API model can coexist under similar product naming.
Sources & Further Reading
- www.anthropic.com — documentation/reference (supplier-provided reference; not independently checked in this pass)
- platform.claude.com — documentation/reference (supplier-provided reference; not independently checked in this pass)
Source documentation establishes vendor-published facts, not independently measured model quality, tenant access, contractual rights or current prices. Use a dated pricing ledger and an account-specific entitlement check for deployment decisions.