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Key Takeaways

  • Now live: ByteDance Seed 2.1 Turbo (dola-seed-2-1-turbo-260628) is available on APIYI for the default / svip groups
  • Both endpoints verified: Chat Completions and Responses passed 15/15 test cases — measured, not just listed
  • Production-grade pricing: $0.50 input / $2.50 output per 1M tokens, officially positioned at half the price of the same-generation Seed 2.1 Pro
  • Controllable deep thinking: on by default, with a one-line off switch and low/high tiers that differ ~4x in measured reasoning tokens
  • Two-layer caching: implicit cache hits automatically from the 2nd request; explicit caching on Responses with chained calls hits the full context and roughly halves latency

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Background

Seed 2.1 Turbo is a production-grade text model released by ByteDance’s Seed team on June 23, 2026 (BytePlus product name: Dola-Seed-2.1-turbo). Sharing a generation with the flagship Seed 2.1 Pro, it targets low-cost, low-latency enterprise workloads at high request volume, with a family-rated 256K context window. Unlike listings that are “live but unverified”, APIYI ran a full two-endpoint test suite before launch: basic chat, streaming, structured output, two-turn function calling, thinking toggle and tiers, implicit/explicit caching, and native multi-turn — 15 cases, all passed. Every number in this article comes from our July 21, 2026 test records.
As of publication (July 21, 2026), no independent third-party benchmarks for the Turbo variant have been published; treat vendor performance-parity claims as unconfirmed until authoritative evaluations land. This article only states behavior we measured ourselves.

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Deep Dive

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Verified capability matrix

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The one thing you must know: thinking is ON by default

Without any extra parameters, deep thinking is enabled by default — even a one-line question first produces hundreds of reasoning tokens. Measured: a one-sentence self-introduction consumed 444 output tokens (409 of them reasoning) and took 7–19 seconds non-streaming. Three control modes, measured:
Reasoning content is billed as regular output tokens. For high-frequency short Q&A, make thinking: {"type": "disabled"} your baseline — measured reasoning tokens drop to zero and responses get dramatically faster.

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Two caching layers — do not mix them up

  • Implicit caching (both endpoints): zero config, a repeated long prefix hits automatically from the 2nd request. Measured: a ~2,600-token system prompt reported 2,360 cached_tokens on request 2.
  • Explicit caching (Responses only): caching: {"type": "enabled"} must be combined with previous_response_id chaining — turn 2 carrying the previous id hits the entire prior context (measured: 7,873 tokens fully cached, latency down from 8s to 4s). Enabling without chaining loses on both fronts: no explicit hits, and the implicit prefix cache stops applying too.

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Putting It to Work

High-frequency Q&A / support bots

With thinking off it is fast and cheap - the $0.50 input price suits heavy traffic.

Agents / tool calling

Two-turn function calling verified stable; Responses adds native multi-turn without resending history.

Long-document multi-turn Q&A

256K family context plus chained explicit caching cuts both cost and latency on long-background follow-ups.

Structured data extraction

json_schema strict mode verified to return valid, complete JSON - ready for batch extraction pipelines.

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Code example

More examples (streaming, tiered thinking, chained caching on Responses) are in the Seed 2.1 Turbo Overview, or send requests directly from the Chat Playground and Responses Playground.

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Best practices

  1. Make thinking disabled the baseline; switch to reasoning_effort tiers only for genuinely complex tasks
  2. With thinking on, give max_tokens / max_output_tokens headroom (3000+) — on Responses a small budget returns incomplete with empty text
  3. Put fixed system prompts first so implicit caching saves money automatically
  4. In error handling, note that a misspelled model name returns 503 (no available channel), not the OpenAI-conventional 404

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Pricing and Availability

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Pricing

The model is open to the default and svip groups. Existing tokens need no configuration change — just switch the model name to dola-seed-2-1-turbo-260628.

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Stack with top-up bonuses

Top-up bonuses lower the effective cost further — see Recharge Promotions.

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Summary

Seed 2.1 Turbo is a “cheap, fast, fully-featured” production model: structured output, function calling, and both caching layers are all verified by measurement, making it a solid primary or fallback for high-frequency workloads. The one thing to get right is the default-on deep thinking — control thinking depth explicitly per task, and the price-performance truly pays off.
Sources: APIYI two-endpoint test records, July 21, 2026; model release information from ByteDance Seed team public materials, June 23, 2026. Prices are list prices at publication time - the console shows real-time pricing.