Pick Doubao Seed 2.0 Pro for powers china's most-used consumer ai app, with strong multimodal reasoning or native video understanding alongside text and image input. Pick GLM 5.1 for long-horizon autonomous agentic engineering (up to 8-hour runs) or state-of-the-art open-weight coding (topped swe-bench pro at launch). Choose GLM 5.1 if you need self-hosting or data privacy; Doubao Seed 2.0 Pro if you want a managed API.
Doubao Seed 2.0 Pro (ByteDance) and GLM 5.1 (Z.ai) are two of the models people most often weigh against each other in 2026. Doubao Seed 2.0 Pro is byteDance's flagship Doubao model — a cheap, multimodal reasoning model behind China's most popular AI app, with strong vendor-claimed benchmarks but undisclosed internals. GLM 5.1 is an open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours. They diverge most on price, context window and open vs. closed weights — each quantified below from the models' real specs.
Key differences
Price: Doubao Seed 2.0 Pro is about 3× cheaper on input ($0.47/$2.37 per 1M tokens vs $1.4/$4.4 per 1M tokens) — meaningful once you are processing millions of tokens a month.
Context window: Doubao Seed 2.0 Pro holds 1.3× more — 256K (~384 pages) vs 200K (~300 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: GLM 5.1 is the newer model by about 52 days (released April 7, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Doubao Seed 2.0 Pro
GLM 5.1
Provider
ByteDance (China)
Z.ai (China)
Released
February 14, 2026
April 7, 2026
Context window
256K (~384 pages)
200K (~300 pages)
Price (in/out)
$0.47/$2.37 per 1M tokens
$1.4/$4.4 per 1M tokens
Open weight?
No — API only
Yes — self-hostable
Modalities
text, image, video, code
text, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Powers China's most-used consumer AI app, with strong multimodal reasoning: Doubao Seed 2.0 Pro — ByteDance's flagship Doubao model — a cheap, multimodal reasoning model behind China's most popular AI app, with strong vendor-claimed benchmarks but undisclosed internals — and it runs cheaper at $0.47/$2.37 per 1M tokens.
Native video understanding alongside text and image input: Doubao Seed 2.0 Pro — Its 256K window holds about 1.3× more than GLM 5.1's 200K in a single prompt.
Aggressively cheap for its claimed capability — around $0.47/$2.37 per million tokens: Doubao Seed 2.0 Pro — At $0.47/$2.37 per 1M tokens it undercuts GLM 5.1 ($1.4/$4.4 per 1M tokens), and that gap compounds at volume.
Long-horizon autonomous agentic engineering (up to 8-hour runs): GLM 5.1 — An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours — and its weights are open while Doubao Seed 2.0 Pro is API-only.
State-of-the-art open-weight coding (topped SWE-Bench Pro at launch): GLM 5.1 — Open weights make this possible at all — Doubao Seed 2.0 Pro is API-only, so it cannot leave the vendor's servers.
Sustained tool use across thousands of calls: GLM 5.1 — An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours — and it is the newer of the two.
Lowest cost at scale: Doubao Seed 2.0 Pro — At $0.47/$2.37 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: Doubao Seed 2.0 Pro — Its 256K window is about 1.3× larger than GLM 5.1's 200K, fitting roughly 384 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Doubao Seed 2.0 Pro — At $0.47/$2.37 per 1M tokens it undercuts GLM 5.1, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Doubao Seed 2.0 Pro — Larger 256K window fits more in one prompt.
A team with data-privacy or self-hosting needs: GLM 5.1 — Open weights let you run it on your own hardware; Doubao Seed 2.0 Pro is API-only.
Anyone whose priority is powers china's most-used consumer ai app, with strong multimodal reasoning: Doubao Seed 2.0 Pro — It is specifically built for that.
Anyone whose priority is long-horizon autonomous agentic engineering (up to 8-hour runs): GLM 5.1 — That is its strongest area.
Doubao Seed 2.0 Pro: where it fits
ByteDance's flagship Doubao model — a cheap, multimodal reasoning model behind China's most popular AI app, with strong vendor-claimed benchmarks but undisclosed internals. Released February 14, 2026 by ByteDance, it is built for powers China's most-used consumer AI app, with strong multimodal reasoning, native video understanding alongside text and image input, aggressively cheap for its claimed capability — around $0.47/$2.37 per million tokens, and byteDance reports frontier-level math and coding scores (e.g. AIME25 98.3, vendor-claimed SWE-Bench Verified 76.5).
Its trade-offs are real: byteDance discloses no parameter count or architecture details, benchmark scores are vendor-claimed; no independent Artificial Analysis index for the Pro variant yet, closed weights on a China-hosted API — data-privacy considerations for sensitive work, and smaller 256K context than the 1M-token Chinese rivals. At $0.47 in / $2.37 out per million tokens, it sits in the budget price band.
GLM 5.1: where it fits
An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours. Released April 7, 2026 by Z.ai, it is built for long-horizon autonomous agentic engineering (up to 8-hour runs), state-of-the-art open-weight coding (topped SWE-Bench Pro at launch), sustained tool use across thousands of calls, and self-hostable under a permissive MIT license.
Its trade-offs: text-only, with no image, audio, or video input, and 754B-parameter MoE demands heavy GPU resources to self-host. At $1.4 in / $4.4 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
The defining split here is open vs. closed. GLM 5.1 gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. Doubao Seed 2.0 Pro gives you a managed, always-updated API with no infrastructure to run. Teams with GPUs, privacy requirements, or huge volume often favour the open model; teams that want zero ops and the latest capabilities favour the closed one. Capability is close enough that this operational question, not the benchmark, usually decides it.
Frequently asked questions
Is Doubao Seed 2.0 Pro or GLM 5.1 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Doubao Seed 2.0 Pro leans toward powers china's most-used consumer ai app, with strong multimodal reasoning while GLM 5.1 leans toward long-horizon autonomous agentic engineering (up to 8-hour runs), and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Doubao Seed 2.0 Pro or GLM 5.1?
GLM 5.1 is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while Doubao Seed 2.0 Pro is API-metered at $0.47/$2.37 per 1M tokens. For most teams without GPUs, the API model is cheaper to start; at very high volume, self-hosting can win.
Which has the bigger context window?
Doubao Seed 2.0 Pro — 256K vs 200K, about 1.3× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Doubao Seed 2.0 Pro and GLM 5.1 together?
Yes — a multi-model platform like LumiChats gives you Doubao Seed 2.0 Pro, GLM 5.1 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Doubao Seed 2.0 Pro or GLM 5.1?
GLM 5.1 — released April 7, 2026, about 52 days after Doubao Seed 2.0 Pro.
Doubao Seed 2.0 Pro vs GLM 5.1
ByteDance · China | Z.ai · China · Updated June 2026
Quick verdict
Pick Doubao Seed 2.0 Pro for powers china's most-used consumer ai app, with strong multimodal reasoning or native video understanding alongside text and image input. Pick GLM 5.1 for long-horizon autonomous agentic engineering (up to 8-hour runs) or state-of-the-art open-weight coding (topped swe-bench pro at launch). Choose GLM 5.1 if you need self-hosting or data privacy; Doubao Seed 2.0 Pro if you want a managed API.
Doubao Seed 2.0 Pro (ByteDance) and GLM 5.1 (Z.ai) are two of the models people most often weigh against each other in 2026. Doubao Seed 2.0 Pro is byteDance's flagship Doubao model — a cheap, multimodal reasoning model behind China's most popular AI app, with strong vendor-claimed benchmarks but undisclosed internals. GLM 5.1 is an open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours. They diverge most on price, context window and open vs. closed weights — each quantified below from the models' real specs.
Key differences at a glance
▸Price: Doubao Seed 2.0 Pro is about 3× cheaper on input ($0.47/$2.37 per 1M tokens vs $1.4/$4.4 per 1M tokens) — meaningful once you are processing millions of tokens a month.
▸Context window: Doubao Seed 2.0 Pro holds 1.3× more — 256K (~384 pages) vs 200K (~300 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: GLM 5.1 is the newer model by about 52 days (released April 7, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Doubao Seed 2.0 Pro
GLM 5.1
Provider
ByteDance (China)
Z.ai (China)
Released
February 14, 2026
April 7, 2026
Context window
256K (~384 pages)
200K (~300 pages)
Price (in/out)
$0.47/$2.37 per 1M tokens
$1.4/$4.4 per 1M tokens
Open weight?
No — API only
Yes — self-hostable
Modalities
text, image, video, code
text, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Powers China's most-used consumer AI app, with strong multimodal reasoning
Doubao Seed 2.0 Pro
ByteDance's flagship Doubao model — a cheap, multimodal reasoning model behind China's most popular AI app, with strong vendor-claimed benchmarks but undisclosed internals — and it runs cheaper at $0.47/$2.37 per 1M tokens.
Native video understanding alongside text and image input
Doubao Seed 2.0 Pro
Its 256K window holds about 1.3× more than GLM 5.1's 200K in a single prompt.
Aggressively cheap for its claimed capability — around $0.47/$2.37 per million tokens
Doubao Seed 2.0 Pro
At $0.47/$2.37 per 1M tokens it undercuts GLM 5.1 ($1.4/$4.4 per 1M tokens), and that gap compounds at volume.
Long-horizon autonomous agentic engineering (up to 8-hour runs)
GLM 5.1
An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours — and its weights are open while Doubao Seed 2.0 Pro is API-only.
State-of-the-art open-weight coding (topped SWE-Bench Pro at launch)
GLM 5.1
Open weights make this possible at all — Doubao Seed 2.0 Pro is API-only, so it cannot leave the vendor's servers.
Sustained tool use across thousands of calls
GLM 5.1
An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours — and it is the newer of the two.
Lowest cost at scale
Doubao Seed 2.0 Pro
At $0.47/$2.37 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
Doubao Seed 2.0 Pro
Its 256K window is about 1.3× larger than GLM 5.1's 200K, fitting roughly 384 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Doubao Seed 2.0 Pro
At $0.47/$2.37 per 1M tokens it undercuts GLM 5.1, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Doubao Seed 2.0 Pro
Larger 256K window fits more in one prompt.
A team with data-privacy or self-hosting needs
→ GLM 5.1
Open weights let you run it on your own hardware; Doubao Seed 2.0 Pro is API-only.
Anyone whose priority is powers china's most-used consumer ai app, with strong multimodal reasoning
→ Doubao Seed 2.0 Pro
It is specifically built for that.
Anyone whose priority is long-horizon autonomous agentic engineering (up to 8-hour runs)
→ GLM 5.1
That is its strongest area.
Doubao Seed 2.0 Pro: where it fits
ByteDance's flagship Doubao model — a cheap, multimodal reasoning model behind China's most popular AI app, with strong vendor-claimed benchmarks but undisclosed internals. Released February 14, 2026 by ByteDance, it is built for powers China's most-used consumer AI app, with strong multimodal reasoning, native video understanding alongside text and image input, aggressively cheap for its claimed capability — around $0.47/$2.37 per million tokens, and byteDance reports frontier-level math and coding scores (e.g. AIME25 98.3, vendor-claimed SWE-Bench Verified 76.5).
Its trade-offs are real: byteDance discloses no parameter count or architecture details, benchmark scores are vendor-claimed; no independent Artificial Analysis index for the Pro variant yet, closed weights on a China-hosted API — data-privacy considerations for sensitive work, and smaller 256K context than the 1M-token Chinese rivals. At $0.47 in / $2.37 out per million tokens, it sits in the budget price band.
GLM 5.1: where it fits
An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours. Released April 7, 2026 by Z.ai, it is built for long-horizon autonomous agentic engineering (up to 8-hour runs), state-of-the-art open-weight coding (topped SWE-Bench Pro at launch), sustained tool use across thousands of calls, and self-hostable under a permissive MIT license.
Its trade-offs: text-only, with no image, audio, or video input, and 754B-parameter MoE demands heavy GPU resources to self-host. At $1.4 in / $4.4 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
The defining split here is open vs. closed. GLM 5.1 gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. Doubao Seed 2.0 Pro gives you a managed, always-updated API with no infrastructure to run. Teams with GPUs, privacy requirements, or huge volume often favour the open model; teams that want zero ops and the latest capabilities favour the closed one. Capability is close enough that this operational question, not the benchmark, usually decides it.
Want both Doubao Seed 2.0 Pro and GLM 5.1 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
Is Doubao Seed 2.0 Pro or GLM 5.1 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Doubao Seed 2.0 Pro leans toward powers china's most-used consumer ai app, with strong multimodal reasoning while GLM 5.1 leans toward long-horizon autonomous agentic engineering (up to 8-hour runs), and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Doubao Seed 2.0 Pro or GLM 5.1?
GLM 5.1 is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while Doubao Seed 2.0 Pro is API-metered at $0.47/$2.37 per 1M tokens. For most teams without GPUs, the API model is cheaper to start; at very high volume, self-hosting can win.
Which has the bigger context window?
Doubao Seed 2.0 Pro — 256K vs 200K, about 1.3× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Doubao Seed 2.0 Pro and GLM 5.1 together?
Yes — a multi-model platform like LumiChats gives you Doubao Seed 2.0 Pro, GLM 5.1 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Doubao Seed 2.0 Pro or GLM 5.1?
GLM 5.1 — released April 7, 2026, about 52 days after Doubao Seed 2.0 Pro.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.