Anthropic SDK reaches v1.0.0 with httpx2 migration
Anthropic's Python SDK has reached v1.0.0, marking a significant infrastructure shift that mirrors OpenAI's recent v3.0.0 overhaul. Both libraries are migrating from httpx to httpx2, a dependency upgrade that affects the entire ecosystem of tools built atop these SDKs. Simon Willison's llm-anthropic plugin now provides compatibility with this new baseline, ensuring developers using the LLM CLI framework can continue working with Anthropic's models without friction. This standardization across major AI providers signals maturation in the Python tooling layer and reduces fragmentation for builders integrating multiple LLM backends.
Modelwire context
Analyst takeThe real story isn't Anthropic's v1.0.0 milestone itself, but that both Anthropic and OpenAI are converging on the same HTTP transport layer (httpx2) at the same time. This removes a technical reason for developers to favor one SDK over another.
This is largely disconnected from recent activity in the space, which has focused on model capability releases and safety research. Instead, it belongs to the infrastructure layer: the unsexy but critical work of standardizing how Python developers talk to LLM APIs. When competing vendors adopt the same underlying dependencies, it signals maturation and reduces switching costs. The fact that Simon Willison's llm-anthropic plugin had to ship compatibility updates shows the dependency upgrade wasn't backward-compatible, which means developers using older versions face a forced migration window.
If other LLM provider SDKs (Cohere, Together, Mistral) adopt httpx2 within the next two quarters, that confirms a genuine ecosystem standard forming. If they don't, or if they stick with httpx, that suggests the convergence is coincidental rather than coordinated.
This analysis is generated by Modelwire’s editorial layer from our archive and the summary above. It is not a substitute for the original reporting. How we write it.
MentionsAnthropic · OpenAI · Simon Willison · llm-anthropic · httpx2 · anthropic-sdk-python
Modelwire Editorial
This synthesis and analysis was prepared by the Modelwire editorial team. We use advanced language models to read, ground, and connect the day’s most significant AI developments, providing original strategic context that helps practitioners and leaders stay ahead of the frontier.
Modelwire summarizes, we don’t republish. Simon Willison originally reported this story as “llm-anthropic 0.27”. The full content lives on simonwillison.net. If you’re a publisher and want a different summarization policy for your work, see our takedown page.