Pick GPT-5.3-Codex for dedicated coding agent or cli and ide integration. Pick Grok 4 for 256k context with native tool use 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 1.7× cheaper on input ($1.75/$14 per 1M tokens vs $3/$15 per 1M tokens) — modest, but it adds up at steady volume.
Context window: GPT-5.3-Codex holds 1.6× more — 400K (~600 pages) vs 256K (~384 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 February 24, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
GPT-5.3-Codex
Grok 4
Provider
OpenAI (US)
xAI (US)
Released
February 24, 2026
July 9, 2025
Context window
400K (~600 pages)
256K (~384 pages)
Price (in/out)
$1.75/$14 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 — OpenAI's coding-specialized agent model for autonomous software engineering — and it runs cheaper at $1.75/$14 per 1M tokens.
CLI and IDE integration: GPT-5.3-Codex — OpenAI's coding-specialized agent model for autonomous software engineering — and it carries the larger 400K context.
Autonomous software tasks: GPT-5.3-Codex — OpenAI's coding-specialized agent model for autonomous software engineering — and it is the newer of the two.
256K context with native tool use: Grok 4 — Grok 4 lists 256K context with native tool use among its strengths; GPT-5.3-Codex does not.
Real-time data via X integration: Grok 4 — Grok 4 lists real-time data via X integration among its strengths; GPT-5.3-Codex does not.
Strong academic reasoning: Grok 4 — Grok 4 lists strong academic reasoning among its strengths; GPT-5.3-Codex does not.
Lowest cost at scale: GPT-5.3-Codex — At $1.75/$14 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: GPT-5.3-Codex — Its 400K window is about 1.6× larger than Grok 4's 256K, fitting roughly 600 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: GPT-5.3-Codex — At $1.75/$14 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: GPT-5.3-Codex — Larger 400K 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 256k context with native tool use: 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 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: where it fits
XAI's 2M-context model with live data access and strong reasoning chops. Released July 9, 2025 by xAI, it is built for 256K context with native tool use, 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; GPT-5.3-Codex holds the larger context; and each leads in its own area — GPT-5.3-Codex for dedicated coding agent, Grok 4 for 256k context with native tool use. 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 256k context with native tool use, 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 — $1.75/$14 per 1M tokens vs $3/$15 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
GPT-5.3-Codex — 400K vs 256K, about 1.6× 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 February 24, 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 256k context with native tool use 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 1.7× cheaper on input ($1.75/$14 per 1M tokens vs $3/$15 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: GPT-5.3-Codex holds 1.6× more — 400K (~600 pages) vs 256K (~384 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 February 24, 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
February 24, 2026
July 9, 2025
Context window
400K (~600 pages)
256K (~384 pages)
Price (in/out)
$1.75/$14 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
OpenAI's coding-specialized agent model for autonomous software engineering — and it runs cheaper at $1.75/$14 per 1M tokens.
CLI and IDE integration
GPT-5.3-Codex
OpenAI's coding-specialized agent model for autonomous software engineering — and it carries the larger 400K context.
Autonomous software tasks
GPT-5.3-Codex
OpenAI's coding-specialized agent model for autonomous software engineering — and it is the newer of the two.
256K context with native tool use
Grok 4
Grok 4 lists 256K context with native tool use among its strengths; GPT-5.3-Codex does not.
Real-time data via X integration
Grok 4
Grok 4 lists real-time data via X integration among its strengths; GPT-5.3-Codex does not.
Strong academic reasoning
Grok 4
Grok 4 lists strong academic reasoning among its strengths; GPT-5.3-Codex does not.
Lowest cost at scale
GPT-5.3-Codex
At $1.75/$14 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-5.3-Codex
Its 400K window is about 1.6× larger than Grok 4's 256K, fitting roughly 600 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-5.3-Codex
At $1.75/$14 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
→ GPT-5.3-Codex
Larger 400K 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 256k context with native tool use
→ 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 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: where it fits
XAI's 2M-context model with live data access and strong reasoning chops. Released July 9, 2025 by xAI, it is built for 256K context with native tool use, 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; GPT-5.3-Codex holds the larger context; and each leads in its own area — GPT-5.3-Codex for dedicated coding agent, Grok 4 for 256k context with native tool use. 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 256k context with native tool use, 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 — $1.75/$14 per 1M tokens vs $3/$15 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
GPT-5.3-Codex — 400K vs 256K, about 1.6× 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 February 24, 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.