Pick GPT-5.3-Codex for dedicated coding agent or cli and ide integration. Pick Grok 4 for 2m production context window or real-time data via x integration. On a tight budget at scale, GPT-5.3-Codex is the value pick.
GPT-5.3-Codex (OpenAI) and Grok 4 (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 is xAI's 2M-context model with live data access and strong reasoning chops. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: GPT-5.3-Codex is about 2× cheaper on input ($1.5/$10 per 1M tokens vs $3/$15 per 1M tokens) — meaningful once you are processing millions of tokens a month.
Context window: Grok 4 holds 16× more — 2M (~3,000 pages) vs 128K (~192 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: GPT-5.3-Codex is the newer model by about 8 months (released 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
GPT-5.3-Codex
Grok 4
Provider
OpenAI (US)
xAI (US)
Released
2026
2025
Context window
128K (~192 pages)
2M (~3,000 pages)
Price (in/out)
$1.5/$10 per 1M tokens
$3/$15 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, code
text, image, 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.
2M production context window: Grok 4 — A core design strength of Grok 4.
Real-time data via X integration: Grok 4 — A core design strength of Grok 4.
Strong academic reasoning: Grok 4 — A core design strength of Grok 4.
Lowest cost at scale: GPT-5.3-Codex — At $1.5/$10 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 — Its 2M window is about 16× larger, fitting roughly 3,000 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: GPT-5.3-Codex — At $1.5/$10 per 1M tokens it undercuts Grok 4, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: Grok 4 — Larger 2M 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 2m production context window: Grok 4 — That is its strongest area.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released 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 $1.5 in / $10 out per million tokens, it sits in the mid price band.
Grok 4: where it fits
XAI's 2M-context model with live data access and strong reasoning chops. Released 2025 by xAI, it is built for 2M production context window, real-time data via X integration, strong academic reasoning, and no long-context surcharge.
Its trade-offs: smaller ecosystem than OpenAI/Google, and less independent benchmark coverage. At $3 in / $15 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-5.3-Codex and Grok 4 overlap enough that the right pick depends on your specific job. GPT-5.3-Codex costs less per token; Grok 4 holds the larger context; and each leads in its own area — GPT-5.3-Codex for dedicated coding agent, Grok 4 for 2m production context window. 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 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 leans toward 2m production context window, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.3-Codex or Grok 4?
GPT-5.3-Codex is cheaper — $1.5/$10 per 1M tokens vs $3/$15 per 1M tokens, roughly 2× apart on input.
Which has the bigger context window?
Grok 4 — 2M vs 128K, about 16× 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 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.3-Codex, Grok 4 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?
GPT-5.3-Codex — released 2026, about 8 months after Grok 4.
GPT-5.3-Codex vs Grok 4
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 for 2m production context window or real-time data via x integration. On a tight budget at scale, GPT-5.3-Codex is the value pick.
GPT-5.3-Codex (OpenAI) and Grok 4 (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 is xAI's 2M-context model with live data access and strong reasoning chops. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: GPT-5.3-Codex is about 2× cheaper on input ($1.5/$10 per 1M tokens vs $3/$15 per 1M tokens) — meaningful once you are processing millions of tokens a month.
▸Context window: Grok 4 holds 16× more — 2M (~3,000 pages) vs 128K (~192 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: GPT-5.3-Codex is the newer model by about 8 months (released 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
GPT-5.3-Codex
Grok 4
Provider
OpenAI (US)
xAI (US)
Released
2026
2025
Context window
128K (~192 pages)
2M (~3,000 pages)
Price (in/out)
$1.5/$10 per 1M tokens
$3/$15 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, code
text, image, 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.
2M production context window
Grok 4
A core design strength of Grok 4.
Real-time data via X integration
Grok 4
A core design strength of Grok 4.
Strong academic reasoning
Grok 4
A core design strength of Grok 4.
Lowest cost at scale
GPT-5.3-Codex
At $1.5/$10 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
Its 2M window is about 16× larger, fitting roughly 3,000 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-5.3-Codex
At $1.5/$10 per 1M tokens it undercuts Grok 4, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Grok 4
Larger 2M 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 2m production context window
→ Grok 4
That is its strongest area.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released 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 $1.5 in / $10 out per million tokens, it sits in the mid price band.
Grok 4: where it fits
XAI's 2M-context model with live data access and strong reasoning chops. Released 2025 by xAI, it is built for 2M production context window, real-time data via X integration, strong academic reasoning, and no long-context surcharge.
Its trade-offs: smaller ecosystem than OpenAI/Google, and less independent benchmark coverage. At $3 in / $15 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-5.3-Codex and Grok 4 overlap enough that the right pick depends on your specific job. GPT-5.3-Codex costs less per token; Grok 4 holds the larger context; and each leads in its own area — GPT-5.3-Codex for dedicated coding agent, Grok 4 for 2m production context window. 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 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 leans toward 2m production context window, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.3-Codex or Grok 4?
GPT-5.3-Codex is cheaper — $1.5/$10 per 1M tokens vs $3/$15 per 1M tokens, roughly 2× apart on input.
Which has the bigger context window?
Grok 4 — 2M vs 128K, about 16× 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 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.3-Codex, Grok 4 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?
GPT-5.3-Codex — released 2026, about 8 months after Grok 4.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.