Model vs model

Claude Opus 4.8 vs A.X-K2

A debate-ready pair page: current winner, strongest alternative, decisive benchmarks, and the warning that should travel with the claim.

Use case · Everyday chatbot
Winner · Claude Opus 4.8
Sources · All public sources

Winner

Claude Opus 4.8

Anthropic

11benchmarks won

Professional reasoning

Versus · Everyday chatbot

Claude Opus 4.8 leads this compare set for everyday chatbot.

Claude Opus 4.811 of 11 wins

Verified and stable

0 shared benchmarks are still too close to call, so the win stays conditional. This compare uses all public sources, with provider-official evidence labeled separately.

Close calls: 0
Sources: All public

Full compare workspace Disagreement page

100%win share

Challenger

A.X-K2

Unknown

0benchmarks won

Chat / text
Reasoning / math / science

The cases in full

Claude Opus 4.8 case

Professional reasoning

A.X-K2 case

Chat / text
Reasoning / math / science

What changes the outcome

Claude Opus 4.8: 87 visible benchmark gaps still leave room for the result to move.
A.X-K2: 126 visible benchmark gaps still leave room for the result to move.

Why this result is surprising

The visible shared evidence is more decisive than usual for this compare set.
Very few shared benchmarks are decisively separating these models.

Why this is not a clean win

0 shared benchmarks are still too close to call, so the win stays conditional. This compare uses all public sources, with provider-official evidence labeled separately.
A.X-K2 remains the strongest alternative once you change use case, mode, or missing-evidence assumptions.

Open full compare workspace Open evidence page Open disagreement page

Decisive benchmarks

11 of 138 benchmarks


Intelligence Index AA · index Text · Chat / text	5797.9% exact aliasverified runtime Row details Raw value 57 Percentile 97.9% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	35n/a exact aliasverified runtimeContext only Row details Raw value 35 Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
Coding Index AA · index Code · Coding	7495.2% exact aliasverified runtime Row details Raw value 74 Percentile 95.2% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	39n/a exact aliasverified runtimeContext only Row details Raw value 39 Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
Agentic Index AA · index Code · Coding	4991% exact aliasverified runtime Row details Raw value 49 Percentile 91% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	26n/a exact aliasverified runtimeContext only Row details Raw value 26 Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
GPQA AA · % Text · Reasoning / math / science	92%96.7% exact aliasverified runtime Row details Raw value 92% Percentile 96.7% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	85.7%n/a exact aliasverified runtimeContext only Row details Raw value 85.7% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
Humanity's Last Exam AA · % Text · Reasoning / math / science	48.7%98.9% exact aliasverified runtime Row details Raw value 48.7% Percentile 98.9% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	29.6%n/a exact aliasverified runtimeContext only Row details Raw value 29.6% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
CritPt AA · % Text · Reasoning / math / science	20.9%97.3% exact aliasverified runtime Row details Raw value 20.9% Percentile 97.3% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	8.9%n/a exact aliasverified runtimeContext only Row details Raw value 8.9% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
SciCode AA · % Code · Coding	53.5%96.6% exact aliasverified runtime Row details Raw value 53.5% Percentile 96.6% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	38.5%n/a exact aliasverified runtimeContext only Row details Raw value 38.5% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
AA-Omniscience accuracy AA · % Text · Chat / text	48.8%95.9% exact aliasverified runtime Row details Raw value 48.8% Percentile 95.9% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	18.6%n/a exact aliasverified runtimeContext only Row details Raw value 18.6% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
AA-Omniscience non-hallucination AA · % Text · Chat / text	60.7%90.2% exact aliasverified runtime Row details Raw value 60.7% Percentile 90.2% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	67%n/a exact aliasverified runtimeContext only Row details Raw value 67% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
GDPval-AA AA · rating Text · Professional reasoning	1,58492.9% exact aliasverified runtime Row details Raw value 1,584 Percentile 92.9% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	1,109n/a exact aliasverified runtimeContext only Row details Raw value 1,109 Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a
Long Context Reasoning AA · % Document · Long context	73%90.9% exact aliasverified runtime Row details Raw value 73% Percentile 90.9% Last updated recent Eligibility headline eligible Identity provider alias (0.94) Source label Claude Opus 4.8 (Adaptive Reasoning, Max Effort) Source row	66%n/a exact aliasverified runtimeContext only Row details Raw value 66% Percentile n/a Last updated recent Eligibility benchmark_derived_model Identity provider alias (0.94) Source label A.X-K2 Source row	n/a

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Intelligence Index

AA · index

Text · Chat / text

5797.9%

exact aliasverified runtime

Row details

Raw value: 57
Percentile: 97.9%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

35n/a

exact aliasverified runtimeContext only

Row details

Raw value: 35
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

Coding Index

AA · index

Code · Coding

7495.2%

exact aliasverified runtime

Row details

Raw value: 74
Percentile: 95.2%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

39n/a

exact aliasverified runtimeContext only

Row details

Raw value: 39
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

Agentic Index

AA · index

Code · Coding

4991%

exact aliasverified runtime

Row details

Raw value: 49
Percentile: 91%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

26n/a

exact aliasverified runtimeContext only

Row details

Raw value: 26
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

GPQA

AA · %

Text · Reasoning / math / science

92%96.7%

exact aliasverified runtime

Row details

Raw value: 92%
Percentile: 96.7%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

85.7%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 85.7%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

Humanity's Last Exam

AA · %

Text · Reasoning / math / science

48.7%98.9%

exact aliasverified runtime

Row details

Raw value: 48.7%
Percentile: 98.9%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

29.6%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 29.6%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

CritPt

AA · %

Text · Reasoning / math / science

20.9%97.3%

exact aliasverified runtime

Row details

Raw value: 20.9%
Percentile: 97.3%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

8.9%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 8.9%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

SciCode

AA · %

Code · Coding

53.5%96.6%

exact aliasverified runtime

Row details

Raw value: 53.5%
Percentile: 96.6%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

38.5%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 38.5%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

AA-Omniscience accuracy

AA · %

Text · Chat / text

48.8%95.9%

exact aliasverified runtime

Row details

Raw value: 48.8%
Percentile: 95.9%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

18.6%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 18.6%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

AA-Omniscience non-hallucination

AA · %

Text · Chat / text

60.7%90.2%

exact aliasverified runtime

Row details

Raw value: 60.7%
Percentile: 90.2%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

67%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 67%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

GDPval-AA

AA · rating

Text · Professional reasoning

1,58492.9%

exact aliasverified runtime

Row details

Raw value: 1,584
Percentile: 92.9%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

1,109n/a

exact aliasverified runtimeContext only

Row details

Raw value: 1,109
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

Long Context Reasoning

AA · %

Document · Long context

73%90.9%

exact aliasverified runtime

Row details

Raw value: 73%
Percentile: 90.9%
Last updated: recent
Eligibility: headline eligible
Identity: provider alias (0.94)
Source label: Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source row

66%n/a

exact aliasverified runtimeContext only

Row details

Raw value: 66%
Percentile: n/a
Last updated: recent
Eligibility: benchmark_derived_model
Identity: provider alias (0.94)
Source label: A.X-K2

Source row

n/a

Claude Opus 4.8 vs A.X-K2

Claude Opus 4.8

Claude Opus 4.8 leads this compare set for everyday chatbot.

A.X-K2

Claude Opus 4.8 case

A.X-K2 case

What changes the outcome

Why this result is surprising

Why this is not a clean win

Share the recommendation with the source data attached.

Open or copy the stable surfaces

Use the exact public framing

Pick the voice before you post

Compose a post that keeps the warning attached

Decisive benchmarks

Loading model comparison.

Claude Opus 4.8 vs A.X-K2

Claude Opus 4.8

Claude Opus 4.8 leads this compare set for everyday chatbot.

A.X-K2

Claude Opus 4.8 case

A.X-K2 case

What changes the outcome

Why this result is surprising

Why this is not a clean win

Share the recommendation with the source data attached.

Open or copy the stable surfaces

Use the exact public framing

Pick the voice before you post

Compose a post that keeps the warning attached

Decisive benchmarks