AionLabs: Aion-2.0 vs ByteDance Seed: Seed-2.0-Lite

AionLabs: Aion-2.0 is a text model from AionLabs, released on 23 February 2026. ByteDance Seed: Seed-2.0-Lite is a text model from ByteDance Seed, released on 10 March 2026. Both are listed on api14 under the text category, and both take text in and return text out, so at the level of basic input and output they are the same kind of tool. The differences show up in context size, in what each accepts as input, and in the parameters each supports.

Seed-2.0-Lite has the larger context window at 262144 tokens, twice the 131072 tokens available on Aion-2.0. Seed-2.0-Lite also accepts image and video input alongside text, while Aion-2.0 accepts text only. On parameters, Seed-2.0-Lite supports structured outputs and reasoning effort, and it exposes frequency penalty and stop, none of which appear on Aion-2.0's list. Aion-2.0 supports include_reasoning and reasoning, as does Seed-2.0-Lite, so reasoning is available on both. Both support tools, tool choice, response format, temperature, top p and max tokens. On price, Seed-2.0-Lite is the cheaper option for input, while Aion-2.0 is cheaper for output; the live table on this page has the actual numbers.

For long documents, large codebases or anything that has to be held in a single prompt, Seed-2.0-Lite is the natural choice because of its larger context. The same applies when the input includes images or video, since Aion-2.0 cannot take those at all. If you need structured outputs or want to tune reasoning effort, Seed-2.0-Lite is the one that exposes those controls. Aion-2.0 makes more sense for text-only work where output volume dominates, since its output pricing is the lower of the two, and for workloads that fit comfortably inside 131072 tokens. If your workload is mostly short prompts with long generated answers, the output side of the bill matters more, which points toward Aion-2.0.

Calling either model through api14 works the same way, because the API is OpenAI compatible. You send a chat completion request to the same endpoint with the same request body, and the only thing that changes is the model id. Use "aion-labs/aion-2.0" to route to Aion-2.0, or "bytedance-seed/seed-2.0-lite" to route to Seed-2.0-Lite. Your client code, authentication and message structure stay as they are, so switching between the two for a test or a fallback is a one line change. Keep in mind that parameters specific to one model, such as structured outputs or reasoning effort on Seed-2.0-Lite, will not apply if you point the same request at Aion-2.0.

There are cases where the cheaper output model is still not the right pick. If a request needs image or video understanding, Aion-2.0 cannot serve it regardless of price, so Seed-2.0-Lite remains the choice. Likewise, if a prompt exceeds 131072 tokens, only Seed-2.0-Lite can hold it. And if your pipeline depends on structured outputs, that capability is listed only for Seed-2.0-Lite, so it stays the better fit even where Aion-2.0 would cost less to run.