AionLabs: Aion-2.0 vs Anthropic: Claude Haiku 4.5

AionLabs: Aion-2.0 is a text model from AionLabs, released on 2026-02-23. Anthropic: Claude Haiku 4.5 is a text model from Anthropic, released on 2025-10-15. Both are served through api14 as chat models in the text category, so either one can sit behind the same client code. The main structural difference is that Aion-2.0 is a single-modality model while Claude Haiku 4.5 accepts more than text.

On capabilities, the two diverge in a few concrete ways. Claude Haiku 4.5 has the larger context window at 200000 tokens against 131072 for Aion-2.0, so it can hold roughly half again as much material in a single call. Claude Haiku 4.5 also accepts image and file inputs alongside text, while Aion-2.0 accepts text only. Both return text output. For structured output, Claude Haiku 4.5 is the one that supports it; Aion-2.0 does not. On reasoning, the qualitative comparison shows no meaningful difference, and the same is true for tool support, so both are reasonable choices when you need function calling or reasoning traces. On price, Aion-2.0 is the cheaper option for both input and output tokens, though the live table on this page has the current numbers.

For task selection, the split follows those facts. If your workload is text in and text out, and cost per token matters more than anything else, Aion-2.0 is the natural default. If you need to pass images or files, or you need a structured output mode rather than parsing free text, Claude Haiku 4.5 is the pick because Aion-2.0 does not offer those. If your prompt plus retrieved context is large enough that 131072 tokens is tight, the 200000 token window on Claude Haiku 4.5 is the deciding factor. If you only need tools or reasoning and your inputs are text, either model works and the cheaper one is the sensible starting point.

Calling either model through api14 is the same operation. Both are exposed through an OpenAI-compatible API, so you keep your existing client, base URL and request shape, and change only the model id string. Send "aion-labs/aion-2.0" for AionLabs and "anthropic/claude-haiku-4.5" for Anthropic. Parameters are largely shared: both accept include_reasoning, max_tokens, reasoning, response_format, temperature, tool_choice, tools and top_p. Claude Haiku 4.5 additionally accepts max_completion_tokens, stop, structured_outputs and top_k, so if you rely on those, keep the Anthropic id. Because the request format does not change, you can route between the two per request, for example sending cheap bulk text jobs to Aion-2.0 and switching the id for calls that carry an image or need structured output.

There are still cases where the pricier model is the better pick despite Aion-2.0 being cheaper on both input and output. Any request that includes an image or a file has to go to Claude Haiku 4.5, since Aion-2.0 takes text only. The same applies when you need structured outputs or the extra sampling controls such as top_k and stop, and when your context exceeds what the smaller window can hold. In those situations the lower token price on Aion-2.0 does not help, because the request cannot be served there at all.