ByteDance has quietly launched the DouBao Seed 2.1 series models on the Volcano Engine official website, including the Pro and Turbo versions, while also updating the Seed-Evolving model. These new models are officially positioned as "the next-generation large model designed for the Coding and Agent era," targeting complex engineering delivery and large-scale production. Compared to the previous generation, Seed 2.1 has made comprehensive upgrades in three directions: Coding engineering delivery, Agent long-chain task execution, and multimodal understanding, with the official claiming these three core capabilities are comparable to GPT-5.5. Doubao-seed-2-1-pro is a flagship deep thinking model for high-complexity scenarios, while Doubao-seed-2-1-turbo is a low-cost, low-latency version for large-scale production. Doubao-seed-evolving uses a dynamic iteration mechanism, releasing at least one version update per week. Regarding pricing, the Pro version's input is 6 yuan per million tokens, and output is 30 yuan per million tokens; the Turbo version's input is 3 yuan per million tokens, and output is 15 yuan per million tokens.