Pick Atria Dawn Preview for best-in-class among tested models on several of shanghai ai lab's own benchmarks, including browsecomp (92.5, ahead of gpt-5.6 sol's 92.2) and deepsearchqa (96.0) or 744b-parameter moe built on a glm-5.2 base, released under a fully open mit license. Pick Claude Sonnet 4.5 for agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch or computer use and gui automation (61.4% osworld at launch). Choose Atria Dawn Preview if you need self-hosting or data privacy; Claude Sonnet 4.5 if you want a managed API.
Atria Dawn Preview (Shanghai AI Laboratory, China) and Claude Sonnet 4.5 (Anthropic, US) line up two different AI ecosystems against each other — a comparison that is as much about cost philosophy and openness as raw capability. Atria Dawn Preview is a free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper. Claude Sonnet 4.5 is september 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. They diverge most on price, context window and open vs. closed weights — each quantified below from the models' real specs.
Key differences
Cost model: Atria Dawn Preview ships open weights you can self-host (hardware cost only, no per-token fee), while Claude Sonnet 4.5 is API-metered at $3/$15 per 1M tokens. Your choice depends on whether you want zero marginal cost at the price of running infrastructure.
Context window: Atria Dawn Preview holds 1.3× more — 256K tokens (~393 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: Atria Dawn Preview is the newer model by about 12 months (released September 11, 2026), usually meaning fresher training data and capabilities.
Ecosystem: this is a China-vs-US matchup — they differ in pricing philosophy, data-residency options, and tooling ecosystems, not only benchmarks.
Specifications
Spec
Atria Dawn Preview
Claude Sonnet 4.5
Provider
Shanghai AI Laboratory (China)
Anthropic (US)
Released
September 11, 2026
September 29, 2025
Context window
256K tokens (~393 pages)
200K (~300 pages)
Price (in/out)
Open weight (self-host / free)
$3/$15 per 1M tokens
Open weight?
Yes — self-hostable
No — API only
Modalities
text
text, image, code
SWE-Bench Verified
Not published
77.2%
MRCR v2 @ 1M
Not published
Not published
Who wins what
Best-in-class among tested models on several of Shanghai AI Lab's own benchmarks, including BrowseComp (92.5, ahead of GPT-5.6 Sol's 92.2) and DeepSearchQA (96.0): Atria Dawn Preview — A free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper — and it carries the larger 256K tokens context.
744B-parameter MoE built on a GLM-5.2 base, released under a fully open MIT license: Atria Dawn Preview — Open weights make this possible at all — Claude Sonnet 4.5 is API-only, so it cannot leave the vendor's servers.
Free to self-host — no API pricing, run entirely on your own hardware: Atria Dawn Preview — A free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper — and its weights are open while Claude Sonnet 4.5 is API-only.
Agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch: Claude Sonnet 4.5 — Atria Dawn Preview is comparatively weak here — released quietly, with weights and an API posted to GitHub before Shanghai AI Lab's own technical report went up on arXiv days later
Computer use and GUI automation (61.4% OSWorld at launch): Claude Sonnet 4.5 — Claude Sonnet 4.5 lists computer use and GUI automation (61.4% OSWorld at launch) among its strengths; Atria Dawn Preview does not.
Long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks: Claude Sonnet 4.5 — Atria Dawn Preview is comparatively weak here — context window is reported inconsistently across trackers — most list 256K tokens, at least one lists 1M; unconfirmed which is accurate
Lowest cost at scale: Atria Dawn Preview — Its weights are open, so at volume you pay for your own hardware instead of Claude Sonnet 4.5's $3/$15 per 1M tokens.
Largest single-prompt input: Atria Dawn Preview — Its 256K tokens window is about 1.3× larger than Claude Sonnet 4.5's 200K, fitting roughly 393 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Atria Dawn Preview — At Open weight (self-host / free) it undercuts Claude Sonnet 4.5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Atria Dawn Preview — Larger 256K tokens window fits more in one prompt.
A team with data-privacy or self-hosting needs: Atria Dawn Preview — Open weights let you run it on your own hardware; Claude Sonnet 4.5 is API-only.
Anyone whose priority is best-in-class among tested models on several of shanghai ai lab's own benchmarks, including browsecomp (92.5, ahead of gpt-5.6 sol's 92.2) and deepsearchqa (96.0): Atria Dawn Preview — It is specifically built for that.
Anyone whose priority is agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch: Claude Sonnet 4.5 — That is its strongest area.
An enterprise with regional data-residency rules: Claude Sonnet 4.5 or Atria Dawn Preview — Origin (China vs US) affects where data is processed and which compliance regime applies — check the provider's terms for your region.
Atria Dawn Preview: where it fits
A free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper. Released September 11, 2026 by Shanghai AI Laboratory, it is built for best-in-class among tested models on several of Shanghai AI Lab's own benchmarks, including BrowseComp (92.5, ahead of GPT-5.6 Sol's 92.2) and DeepSearchQA (96.0), 744B-parameter MoE built on a GLM-5.2 base, released under a fully open MIT license, and free to self-host — no API pricing, run entirely on your own hardware.
Its trade-offs are real: context window is reported inconsistently across trackers — most list 256K tokens, at least one lists 1M; unconfirmed which is accurate, released quietly, with weights and an API posted to GitHub before Shanghai AI Lab's own technical report went up on arXiv days later, and a lab research preview rather than a commercial product — support and update cadence are unclear. As an open-weight model, its running cost is your own hardware rather than a per-token fee.
Claude Sonnet 4.5: where it fits
September 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. Released September 29, 2025 by Anthropic, it is built for agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch, computer use and GUI automation (61.4% OSWorld at launch), long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks, and tracking its own remaining token budget natively, which few models do.
Its trade-offs: superseded twice — Sonnet 4.6 and Sonnet 5 match or beat it at the same or lower price, capped at 200K since Anthropic retired its 1M beta in April 2026, while its successors ship 1M as standard, and missing the modern API surface: no adaptive thinking, no effort control, and half the max output of newer Sonnets. At $3 in / $15 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. Atria Dawn Preview gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. Claude Sonnet 4.5 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 Atria Dawn Preview or Claude Sonnet 4.5 better for coding?
Public SWE-Bench figures are not available for Atria Dawn Preview, so the honest test is your own repository — run an identical real bug through both. By design, Atria Dawn Preview leans toward best-in-class among tested models on several of shanghai ai lab's own benchmarks, including browsecomp (92.5, ahead of gpt-5.6 sol's 92.2) and deepsearchqa (96.0) while Claude Sonnet 4.5 leans toward agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Atria Dawn Preview or Claude Sonnet 4.5?
Atria Dawn Preview is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while Claude Sonnet 4.5 is API-metered at $3/$15 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?
Atria Dawn Preview — 256K tokens 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 Atria Dawn Preview and Claude Sonnet 4.5 together?
Yes — a multi-model platform like LumiChats gives you Atria Dawn Preview, Claude Sonnet 4.5 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, Atria Dawn Preview or Claude Sonnet 4.5?
Atria Dawn Preview — released September 11, 2026, about 12 months after Claude Sonnet 4.5.
Atria Dawn Preview vs Claude Sonnet 4.5
Shanghai AI Laboratory · China | Anthropic · US · Updated June 2026
Quick verdict
Pick Atria Dawn Preview for best-in-class among tested models on several of shanghai ai lab's own benchmarks, including browsecomp (92.5, ahead of gpt-5.6 sol's 92.2) and deepsearchqa (96.0) or 744b-parameter moe built on a glm-5.2 base, released under a fully open mit license. Pick Claude Sonnet 4.5 for agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch or computer use and gui automation (61.4% osworld at launch). Choose Atria Dawn Preview if you need self-hosting or data privacy; Claude Sonnet 4.5 if you want a managed API.
Atria Dawn Preview (Shanghai AI Laboratory, China) and Claude Sonnet 4.5 (Anthropic, US) line up two different AI ecosystems against each other — a comparison that is as much about cost philosophy and openness as raw capability. Atria Dawn Preview is a free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper. Claude Sonnet 4.5 is september 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. 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
▸Cost model: Atria Dawn Preview ships open weights you can self-host (hardware cost only, no per-token fee), while Claude Sonnet 4.5 is API-metered at $3/$15 per 1M tokens. Your choice depends on whether you want zero marginal cost at the price of running infrastructure.
▸Context window: Atria Dawn Preview holds 1.3× more — 256K tokens (~393 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: Atria Dawn Preview is the newer model by about 12 months (released September 11, 2026), usually meaning fresher training data and capabilities.
▸Ecosystem: this is a China-vs-US matchup — they differ in pricing philosophy, data-residency options, and tooling ecosystems, not only benchmarks.
Side-by-side specs
Spec
Atria Dawn Preview
Claude Sonnet 4.5
Provider
Shanghai AI Laboratory (China)
Anthropic (US)
Released
September 11, 2026
September 29, 2025
Context window
256K tokens (~393 pages)
200K (~300 pages)
Price (in/out)
Open weight (self-host / free)
$3/$15 per 1M tokens
Open weight?
Yes — self-hostable
No — API only
Modalities
text
text, image, code
SWE-Bench Verified
Not published
77.2%
MRCR v2 @ 1M
Not published
Not published
Who wins what
Best-in-class among tested models on several of Shanghai AI Lab's own benchmarks, including BrowseComp (92.5, ahead of GPT-5.6 Sol's 92.2) and DeepSearchQA (96.0)
Atria Dawn Preview
A free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper — and it carries the larger 256K tokens context.
744B-parameter MoE built on a GLM-5.2 base, released under a fully open MIT license
Atria Dawn Preview
Open weights make this possible at all — Claude Sonnet 4.5 is API-only, so it cannot leave the vendor's servers.
Free to self-host — no API pricing, run entirely on your own hardware
Atria Dawn Preview
A free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper — and its weights are open while Claude Sonnet 4.5 is API-only.
Agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch
Claude Sonnet 4.5
Atria Dawn Preview is comparatively weak here — released quietly, with weights and an API posted to GitHub before Shanghai AI Lab's own technical report went up on arXiv days later
Computer use and GUI automation (61.4% OSWorld at launch)
Claude Sonnet 4.5
Claude Sonnet 4.5 lists computer use and GUI automation (61.4% OSWorld at launch) among its strengths; Atria Dawn Preview does not.
Long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks
Claude Sonnet 4.5
Atria Dawn Preview is comparatively weak here — context window is reported inconsistently across trackers — most list 256K tokens, at least one lists 1M; unconfirmed which is accurate
Lowest cost at scale
Atria Dawn Preview
Its weights are open, so at volume you pay for your own hardware instead of Claude Sonnet 4.5's $3/$15 per 1M tokens.
Largest single-prompt input
Atria Dawn Preview
Its 256K tokens window is about 1.3× larger than Claude Sonnet 4.5's 200K, fitting roughly 393 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Atria Dawn Preview
At Open weight (self-host / free) it undercuts Claude Sonnet 4.5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Atria Dawn Preview
Larger 256K tokens window fits more in one prompt.
A team with data-privacy or self-hosting needs
→ Atria Dawn Preview
Open weights let you run it on your own hardware; Claude Sonnet 4.5 is API-only.
Anyone whose priority is best-in-class among tested models on several of shanghai ai lab's own benchmarks, including browsecomp (92.5, ahead of gpt-5.6 sol's 92.2) and deepsearchqa (96.0)
→ Atria Dawn Preview
It is specifically built for that.
Anyone whose priority is agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch
→ Claude Sonnet 4.5
That is its strongest area.
An enterprise with regional data-residency rules
→ Claude Sonnet 4.5 or Atria Dawn Preview
Origin (China vs US) affects where data is processed and which compliance regime applies — check the provider's terms for your region.
Atria Dawn Preview: where it fits
A free, MIT-licensed 744B open-weight model from Shanghai AI Lab that beat GPT-5.6 Sol on the BrowseComp benchmark — released quietly, weights before paper. Released September 11, 2026 by Shanghai AI Laboratory, it is built for best-in-class among tested models on several of Shanghai AI Lab's own benchmarks, including BrowseComp (92.5, ahead of GPT-5.6 Sol's 92.2) and DeepSearchQA (96.0), 744B-parameter MoE built on a GLM-5.2 base, released under a fully open MIT license, and free to self-host — no API pricing, run entirely on your own hardware.
Its trade-offs are real: context window is reported inconsistently across trackers — most list 256K tokens, at least one lists 1M; unconfirmed which is accurate, released quietly, with weights and an API posted to GitHub before Shanghai AI Lab's own technical report went up on arXiv days later, and a lab research preview rather than a commercial product — support and update cadence are unclear. As an open-weight model, its running cost is your own hardware rather than a per-token fee.
Claude Sonnet 4.5: where it fits
September 2025's coding state of the art at $3/$15 — still supported, but 200K-capped and twice superseded. Released September 29, 2025 by Anthropic, it is built for agentic coding — 77.2% on SWE-Bench Verified, the best score any model had posted at its launch, computer use and GUI automation (61.4% OSWorld at launch), long-horizon autonomy — Anthropic reported 30+ hours of sustained focus on multi-step tasks, and tracking its own remaining token budget natively, which few models do.
Its trade-offs: superseded twice — Sonnet 4.6 and Sonnet 5 match or beat it at the same or lower price, capped at 200K since Anthropic retired its 1M beta in April 2026, while its successors ship 1M as standard, and missing the modern API surface: no adaptive thinking, no effort control, and half the max output of newer Sonnets. At $3 in / $15 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. Atria Dawn Preview gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. Claude Sonnet 4.5 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 Atria Dawn Preview and Claude Sonnet 4.5 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 Atria Dawn Preview or Claude Sonnet 4.5 better for coding?
Public SWE-Bench figures are not available for Atria Dawn Preview, so the honest test is your own repository — run an identical real bug through both. By design, Atria Dawn Preview leans toward best-in-class among tested models on several of shanghai ai lab's own benchmarks, including browsecomp (92.5, ahead of gpt-5.6 sol's 92.2) and deepsearchqa (96.0) while Claude Sonnet 4.5 leans toward agentic coding — 77.2% on swe-bench verified, the best score any model had posted at its launch, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Atria Dawn Preview or Claude Sonnet 4.5?
Atria Dawn Preview is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while Claude Sonnet 4.5 is API-metered at $3/$15 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?
Atria Dawn Preview — 256K tokens 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 Atria Dawn Preview and Claude Sonnet 4.5 together?
Yes — a multi-model platform like LumiChats gives you Atria Dawn Preview, Claude Sonnet 4.5 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, Atria Dawn Preview or Claude Sonnet 4.5?
Atria Dawn Preview — released September 11, 2026, about 12 months after Claude Sonnet 4.5.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.