GLM-5.3-Flash vs Doubao Seed 2.1 Turbo
GLM-5.3-Flash wins on Overall; Doubao Seed 2.1 Turbo wins on Coding, Multimodal. Every numeric field is compared below, with a worked monthly-cost example and a pick rule for each use case.
Verdict at a glance
Choose GLM-5.3-Flash if you…
- Among the cheapest
- Fast
- Open source
- Best for: Ultra-fast, Ultra-low-cost, High concurrency
Choose Doubao Seed 2.1 Turbo if you…
- Low price
- Video support
- Fast
- Built for volume
- Best for: Volume production, Video, Low cost
Head-to-head aggregate scores
Scores are 0–100, aggregated from public benchmark information and independently weighted across three leaderboards. Rank is out of 22 tracked models.
Aggregated from public sources and independently weighted; methodology on the Terms page. Scores within 3 points are treated as statistically tied.
Specs & pricing — every field side by side
List API prices in USD per 1M tokens. The highlighted cell is the stronger value/capability on that row.
| Dimension | GLM-5.3-Flash | Doubao Seed 2.1 Turbo | Verdict |
|---|---|---|---|
| Vendor | Zhipu AI (CN) | ByteDance (CN) | Different vendors |
| Released | 2026.08 | 2026.06 | GLM-5.3-Flash is newer |
| Overall (rank) | 65 · #18 | 63 · #20 | GLM-5.3-Flash +2 |
| Coding | 60 · #20 | 61 · #19 | Doubao Seed 2.1 Turbo +1 |
| Multimodal | 63 · #21 | 73 · #17 | Doubao Seed 2.1 Turbo +10 |
| Context window | 128K | 256K | Doubao Seed 2.1 Turbo larger |
| Max output | 64K | 256K | GLM-5.3-Flash longer |
| Effective-context | 80 | 90 | Doubao Seed 2.1 Turbo more reliable |
| Input $/1M | $0.07 | $0.42 | GLM-5.3-Flash cheaper |
| Output $/1M | $0.25 | $2.08 | GLM-5.3-Flash cheaper |
| Cache discount | none | custom | Doubao Seed 2.1 Turbo deeper |
| Speed | ~90 tok/s | ~75 tok/s | GLM-5.3-Flash faster |
| TTFT | 0.2s | 0.4s | GLM-5.3-Flash snappier |
| Function calling | 70 | 80 | Doubao Seed 2.1 Turbo ahead |
| Refusal rate | ~6% | ~10% | GLM-5.3-Flash less restrictive |
| English | 65 | 68 | Doubao Seed 2.1 Turbo |
| Chinese | 85 | 90 | Doubao Seed 2.1 Turbo |
| Modalities | text | text, image, video | different coverage |
| Open weights | Yes | No | GLM-5.3-Flash is open |
| Fine-tuning | Yes | Yes | |
| Free tier | ChatGLM free | Doubao App free | |
| SOC2 / no-train | no / yes | no / yes | |
| Private deployment | Yes | Yes | Both support it |
Fields drawn from vendor public documentation and the Modelspectra 22-model dataset; speed varies with network, concurrency and prompt length. Verify current pricing before purchase.
Dimension-by-dimension analysis
Reasoning & overall intelligence
GLM-5.3-Flash leads the overall aggregate by 2 points (65 vs 63). That is a meaningful, not marginal, edge on hard, multi-step reasoning, while Doubao Seed 2.1 Turbo remains a strong generalist that is not out of its depth on routine work.
Agentic coding
This is a modest gap: Doubao Seed 2.1 Turbo scores 61 against 60. On multi-file edits, SWE-style tickets and long-horizon agent loops Doubao Seed 2.1 Turbo needs fewer correction turns; GLM-5.3-Flash is still competent for scripts and assisted completion but trails as task complexity rises.
Multimodal
Doubao Seed 2.1 Turbo leads multimodal 73 vs 63. A concrete modality difference: Doubao Seed 2.1 Turbo additionally handles image, video.
Speed & latency
GLM-5.3-Flash is faster in interactive use: ~90 tok/s with 0.2s TTFT versus ~75 tok/s with 0.4s TTFT (about 1.2× the throughput). For conversational UIs where perceived responsiveness drives retention, that edge is a real product factor even when raw reasoning is lower.
Context: window vs usable recall
Nominal windows are 128K for GLM-5.3-Flash and 256K for Doubao Seed 2.1 Turbo. Effective-context scores point the same way as window size — Doubao Seed 2.1 Turbo is ahead on usable recall (90 vs 80), so prefer it for long-document work where details cannot be missed.
Price & total cost
GLM-5.3-Flash is the cheaper API at $0.07/$0.25 versus Doubao Seed 2.1 Turbo at $0.42/$2.08 per 1M input/output tokens — list input is about 5.6× lower.
Chinese vs English
English: GLM-5.3-Flash 65 vs Doubao Seed 2.1 Turbo 68. Chinese: 85 vs 90. For Chinese-language production, Doubao Seed 2.1 Turbo is the stronger pick. Note that non-Chinese models generally require overseas network access for their APIs.
Tool use & ecosystem
Function-calling score: GLM-5.3-Flash 70 vs Doubao Seed 2.1 Turbo 80, so Doubao Seed 2.1 Turbo has the edge on structured tool use. Fine-tuning is available from GLM-5.3-Flash and Doubao Seed 2.1 Turbo. Factor in existing SDK/plugin familiarity — switching cost often outweighs a few-point tool-use gap.
Cost worked example — same workload, real token math
Assume a production workload of 100M input + 30M output tokens per month, with 90% of input tokens served from cache. Figures use public list prices.
| Scenario · per month | GLM-5.3-Flash | Doubao Seed 2.1 Turbo | Gap |
|---|---|---|---|
| List priceno cache applied | $15100M in × $0.07 + 30M out × $0.25 | $104100M in × $0.42 + 30M out × $2.08 | 6.93×gap |
| With caching90% of inputs cache-hit | $15no published cache discount | $104no published cache discount | 6.93×gap |
Illustrative model; your input/output mix and cache-hit ratio change the result. Prices are list rates before any enterprise agreement.