What is the best alternative to GPT-5.3-Codex?

Claude Opus 4.7 is the closest model that scores higher on the BenchLeader Index (63.1 against 62.9). For less money, GPT-6.1 Sol scores 67.2 at $4.00 per 1M tokens.

Is there a cheaper alternative to GPT-5.3-Codex?

Yes: GPT-6.1 Sol (67.2, $4.00), Gemini 4 Argon (65.9, $4.00) and GPT-6.1 Terra (65.2, $2.00), each within 4 Index points and cheaper than GPT-5.3-Codex's $4.81.

Is there an open-source alternative to GPT-5.3-Codex?

The best open-weights models on the BenchLeader Index are Kimi K3 (62.1), GLM-5 (60.2) and GLM 5.2 (60.1). You can download and run them yourself; check each licence on its model page.

How are these alternatives chosen?

From the models ranked on the BenchLeader Index today: the ones just above GPT-5.3-Codex, cheaper ones within 4 points, ones at least 1.5× as fast within 4 points, and the best open-weights models. Prices are list prices blended three input tokens to one output.

OpenAI

GPT-5.3-Codex alternatives

Data as of 2 Nov 2026 · ranked on the BenchLeader Index

As of 2 Nov 2026, GPT-5.3-Codex by OpenAI scores 62.9 on the BenchLeader Index at $4.81 per 1M tokens blended. Claude Opus 4.7 scores higher (63.1); GPT-6.1 Sol is the best cheaper model within 4 points (67.2 at $4.00); Gemini 3.5 Flash is at least 1.5× as fast at a similar score; Kimi K3 is the best open-weights option (62.1).

Scores higher

The closest models above GPT-5.3-Codex on the Index.

Claude Opus 4.7 Anthropic compare63.1 · $10.00
GPT-5.4 Pro OpenAI compare63.1 · $67.50
GPT-5.4 OpenAI compare63.3 · $5.63

Cheaper, nearly as good

Within 4 Index points, for less per token.

GPT-6.1 Sol OpenAI compare67.2 · $4.00
Gemini 4 Argon Google compare65.9 · $4.00
GPT-6.1 Terra OpenAI compare65.2 · $2.00
Claude Sonnet 5.5 Anthropic compare65.1 · $4.00
GPT-6 Sol OpenAI compare63.5 · $4.00

Faster

At least 1.5× the output speed, within 4 points.

Gemini 3.5 Flash Google compare62.5 · $3.38
Muse Spark 1.1 Meta compare62.2 · $2.00
Muse Spark 1.3 Meta compare61.9 · $2.00

Open weights

The best models whose weights you can run yourself.

Kimi K3 Moonshot AI compare62.1 · $6.00
GLM-5 Zhipu AI60.2 · $1.55
GLM 5.2 Zhipu AI60.1 · $2.15

Every alternative side by side

Model	Index	$ / 1M blended	Tokens / s	Why
GPT-5.3-Codex (this model)	62.9	$4.81	114	–
GPT-6.1 Sol	67.2	$4.00	87	cheaper
Gemini 4 Argon	65.9	$4.00	83	cheaper
GPT-6.1 Terra	65.2	$2.00	107	cheaper
Claude Sonnet 5.5	65.1	$4.00	137	cheaper
GPT-6 Sol	63.5	$4.00	149	cheaper
GPT-5.4	63.3	$5.63	108	scores higher
Claude Opus 4.7	63.1	$10.00	49	scores higher
GPT-5.4 Pro	63.1	$67.50	7	scores higher
Gemini 3.5 Flash	62.5	$3.38	190	faster
Muse Spark 1.1	62.2	$2.00	206	faster
Kimi K3	62.1	$6.00	66	open weights
Muse Spark 1.3	61.9	$2.00	194	faster
GLM-5	60.2	$1.55	62	open weights
GLM 5.2	60.1	$2.15	89	open weights

Prices are list prices blended three input tokens to one output; speeds are measured medians, credited on each model page. The Index is BenchLeader's own, from independent benchmarks.

Questions people ask

What is the best alternative to GPT-5.3-Codex?: Claude Opus 4.7 is the closest model that scores higher on the BenchLeader Index (63.1 against 62.9). For less money, GPT-6.1 Sol scores 67.2 at $4.00 per 1M tokens.
Is there a cheaper alternative to GPT-5.3-Codex?: Yes: GPT-6.1 Sol (67.2, $4.00), Gemini 4 Argon (65.9, $4.00) and GPT-6.1 Terra (65.2, $2.00), each within 4 Index points and cheaper than GPT-5.3-Codex's $4.81.
Is there an open-source alternative to GPT-5.3-Codex?: The best open-weights models on the BenchLeader Index are Kimi K3 (62.1), GLM-5 (60.2) and GLM 5.2 (60.1). You can download and run them yourself; check each licence on its model page.
How are these alternatives chosen?: From the models ranked on the BenchLeader Index today: the ones just above GPT-5.3-Codex, cheaper ones within 4 points, ones at least 1.5× as fast within 4 points, and the best open-weights models. Prices are list prices blended three input tokens to one output.