Pick GPT-5.3-Codex for dedicated coding agent or cli and ide integration. Pick Grok 4.3 for video understanding from native video input or generating pdf, pptx, and xlsx files directly. On a tight budget at scale, Grok 4.3 is the value pick.
GPT-5.3-Codex (OpenAI) and Grok 4.3 (xAI) are two of the models people most often weigh against each other in 2026. GPT-5.3-Codex is openAI's coding-specialized agent model for autonomous software engineering. Grok 4.3 is the current xAI flagship: 1M context, native video input, file generation, and live X data, ahead of the still-unreleased Grok 5. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: Grok 4.3 is about 1.4× cheaper on input ($1.25/$2.5 per 1M tokens vs $1.75/$14 per 1M tokens) — modest, but it adds up at steady volume.
Context window: Grok 4.3 holds 2.5× more — 1M (~1,500 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: Grok 4.3 is the newer model by about 2 months (released April 30, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
GPT-5.3-Codex
Grok 4.3
Provider
OpenAI (US)
xAI (US)
Released
February 24, 2026
April 30, 2026
Context window
400K (~600 pages)
1M (~1,500 pages)
Price (in/out)
$1.75/$14 per 1M tokens
$1.25/$2.5 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, code
text, image, video, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Dedicated coding agent: GPT-5.3-Codex — A core design strength of GPT-5.3-Codex.
CLI and IDE integration: GPT-5.3-Codex — A core design strength of GPT-5.3-Codex.
Autonomous software tasks: GPT-5.3-Codex — A core design strength of GPT-5.3-Codex.
Video understanding from native video input: Grok 4.3 — A core design strength of Grok 4.3.
Generating PDF, PPTX, and XLSX files directly: Grok 4.3 — A core design strength of Grok 4.3.
Real-time questions using live X data: Grok 4.3 — A core design strength of Grok 4.3.
Lowest cost at scale: Grok 4.3 — At $1.25/$2.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: Grok 4.3 — Its 1M window is about 2.5× larger, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Grok 4.3 — At $1.25/$2.5 per 1M tokens it undercuts GPT-5.3-Codex, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Grok 4.3 — Larger 1M window fits more in one prompt.
Anyone whose priority is dedicated coding agent: GPT-5.3-Codex — It is specifically built for that.
Anyone whose priority is video understanding from native video input: Grok 4.3 — That is its strongest area.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released February 24, 2026 by OpenAI, it is built for dedicated coding agent, cLI and IDE integration, autonomous software tasks, and tool calling.
Its trade-offs are real: coding-specialized, narrower general use, and retired in favor of GPT-5.5 Codex. At $1.75 in / $14 out per million tokens, it sits in the mid price band.
Grok 4.3: where it fits
The current xAI flagship: 1M context, native video input, file generation, and live X data, ahead of the still-unreleased Grok 5. Released April 30, 2026 by xAI, it is built for video understanding from native video input, generating PDF, PPTX, and XLSX files directly, real-time questions using live X data, and long-context, multi-agent reasoning.
Its trade-offs: higher context pricing on requests above 200K tokens, and less independent benchmark coverage than OpenAI, Anthropic, or Google. At $1.25 in / $2.5 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-5.3-Codex and Grok 4.3 overlap enough that the right pick depends on your specific job. Grok 4.3 costs less per token; Grok 4.3 holds the larger context; and each leads in its own area — GPT-5.3-Codex for dedicated coding agent, Grok 4.3 for video understanding from native video input. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is GPT-5.3-Codex or Grok 4.3 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, GPT-5.3-Codex leans toward dedicated coding agent while Grok 4.3 leans toward video understanding from native video input, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.3-Codex or Grok 4.3?
Grok 4.3 is cheaper — $1.75/$14 per 1M tokens vs $1.25/$2.5 per 1M tokens, roughly 1.4× apart on input.
Which has the bigger context window?
Grok 4.3 — 1M vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both GPT-5.3-Codex and Grok 4.3 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.3-Codex, Grok 4.3 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, GPT-5.3-Codex or Grok 4.3?
Grok 4.3 — released April 30, 2026, about 2 months after GPT-5.3-Codex.
GPT-5.3-Codex vs Grok 4.3
OpenAI · US | xAI · US · Updated June 2026
Quick verdict
Pick GPT-5.3-Codex for dedicated coding agent or cli and ide integration. Pick Grok 4.3 for video understanding from native video input or generating pdf, pptx, and xlsx files directly. On a tight budget at scale, Grok 4.3 is the value pick.
GPT-5.3-Codex (OpenAI) and Grok 4.3 (xAI) are two of the models people most often weigh against each other in 2026. GPT-5.3-Codex is openAI's coding-specialized agent model for autonomous software engineering. Grok 4.3 is the current xAI flagship: 1M context, native video input, file generation, and live X data, ahead of the still-unreleased Grok 5. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: Grok 4.3 is about 1.4× cheaper on input ($1.25/$2.5 per 1M tokens vs $1.75/$14 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: Grok 4.3 holds 2.5× more — 1M (~1,500 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: Grok 4.3 is the newer model by about 2 months (released April 30, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
GPT-5.3-Codex
Grok 4.3
Provider
OpenAI (US)
xAI (US)
Released
February 24, 2026
April 30, 2026
Context window
400K (~600 pages)
1M (~1,500 pages)
Price (in/out)
$1.75/$14 per 1M tokens
$1.25/$2.5 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, code
text, image, video, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Dedicated coding agent
GPT-5.3-Codex
A core design strength of GPT-5.3-Codex.
CLI and IDE integration
GPT-5.3-Codex
A core design strength of GPT-5.3-Codex.
Autonomous software tasks
GPT-5.3-Codex
A core design strength of GPT-5.3-Codex.
Video understanding from native video input
Grok 4.3
A core design strength of Grok 4.3.
Generating PDF, PPTX, and XLSX files directly
Grok 4.3
A core design strength of Grok 4.3.
Real-time questions using live X data
Grok 4.3
A core design strength of Grok 4.3.
Lowest cost at scale
Grok 4.3
At $1.25/$2.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
Grok 4.3
Its 1M window is about 2.5× larger, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Grok 4.3
At $1.25/$2.5 per 1M tokens it undercuts GPT-5.3-Codex, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Grok 4.3
Larger 1M window fits more in one prompt.
Anyone whose priority is dedicated coding agent
→ GPT-5.3-Codex
It is specifically built for that.
Anyone whose priority is video understanding from native video input
→ Grok 4.3
That is its strongest area.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released February 24, 2026 by OpenAI, it is built for dedicated coding agent, cLI and IDE integration, autonomous software tasks, and tool calling.
Its trade-offs are real: coding-specialized, narrower general use, and retired in favor of GPT-5.5 Codex. At $1.75 in / $14 out per million tokens, it sits in the mid price band.
Grok 4.3: where it fits
The current xAI flagship: 1M context, native video input, file generation, and live X data, ahead of the still-unreleased Grok 5. Released April 30, 2026 by xAI, it is built for video understanding from native video input, generating PDF, PPTX, and XLSX files directly, real-time questions using live X data, and long-context, multi-agent reasoning.
Its trade-offs: higher context pricing on requests above 200K tokens, and less independent benchmark coverage than OpenAI, Anthropic, or Google. At $1.25 in / $2.5 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-5.3-Codex and Grok 4.3 overlap enough that the right pick depends on your specific job. Grok 4.3 costs less per token; Grok 4.3 holds the larger context; and each leads in its own area — GPT-5.3-Codex for dedicated coding agent, Grok 4.3 for video understanding from native video input. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both GPT-5.3-Codex and Grok 4.3 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.
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, GPT-5.3-Codex leans toward dedicated coding agent while Grok 4.3 leans toward video understanding from native video input, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.3-Codex or Grok 4.3?
Grok 4.3 is cheaper — $1.75/$14 per 1M tokens vs $1.25/$2.5 per 1M tokens, roughly 1.4× apart on input.
Which has the bigger context window?
Grok 4.3 — 1M vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both GPT-5.3-Codex and Grok 4.3 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.3-Codex, Grok 4.3 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, GPT-5.3-Codex or Grok 4.3?
Grok 4.3 — released April 30, 2026, about 2 months after GPT-5.3-Codex.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.