Which is best for coding in August 2026: Ox Alpha, GPT-5.6 Sol or Claude Opus 5?

Claude Opus 5 and GPT-5.6 Sol are the two defensible production choices; Ox Alpha is not. On a full DeepSWE re-run published August 23, 2026, Ox Alpha landed roughly level with GPT-5.6 Sol mid rather than ahead of it, and the LLM Coding Leaderboard placed it #26 at 8.9 of 20 points. More decisively, Ox Alpha has no identified operator, no data agreement and no price sheet, which disqualifies it from production regardless of score.

How much do these models cost?

Ox Alpha is free during its evaluation window. GPT-5.6 Sol dropped to $4 per million input tokens and $20 per million output on August 21, 2026, down from $5/$30. Claude Opus 5 is $5 input and $25 output per million tokens, unchanged since its July 24, 2026 launch. On a 30K-in/5K-out task that is roughly $0.22 for Sol against $0.275 for Opus 5 — Sol is about 20% cheaper per task after the cut.

Why did Ox Alpha's benchmark score change?

The widely shared 80% Pass@1 figure came from a partial DeepSWE subset run within 48 hours of the model appearing. When the same tester ran the complete benchmark set, the result fell to roughly GPT-5.6 Sol mid parity. The headlines were written from the partial run and mostly not corrected. This is the standard failure mode of same-week benchmark reporting, not a scandal specific to this model.

Can I use a free stealth model to cut my coding costs?

Not for anything proprietary. A free anonymous endpoint has no disclosed retention policy, no named jurisdiction and no contractual counterparty, so you cannot know whether your code becomes training data. If cost is the driver, use a named cheap model instead — Grok 4.6 at $2/$6 or Gemini 3.7 Flash at $0.75/$3.75 give you real coding capability with an actual data agreement behind it.

Quick Answer

Ox Alpha vs GPT-5.6 Sol vs Claude Opus 5: Coding

Published: August 25, 2026

The Short Answer

Claude Opus 5 if code quality on hard agentic tasks is the priority. GPT-5.6 Sol if you want frontier capability at the lowest frontier price — it undercut Opus 5 on August 21, 2026. Ox Alpha for curiosity on public code only, because an unattributed model is not a production dependency at any benchmark score.

The Comparison

	Ox Alpha	GPT-5.6 Sol	Claude Opus 5
Operator	Unknown	OpenAI	Anthropic
Input / MTok	Free (eval window)	$4.00	$5.00
Output / MTok	Free (eval window)	$20.00	$25.00
30K-in / 5K-out task	$0	~$0.22	~$0.275
Context	1,048,576 tokens	Frontier-tier	1M tokens
Multimodal input	Text, image, video	Yes	Yes
Full-set DeepSWE	≈ Sol mid parity	Reference point	Leading tier
Coding Leaderboard	#26, 8.9/20 (medium effort)	Higher	Higher
Data agreement	None	Yes	Yes
Availability guarantee	None — free window	GA	GA

Prices verified August 25, 2026. Sol reflects the August 21 cut from $5/$30.

The Benchmark Correction Nobody Reprinted

Ox Alpha appeared on OpenRouter as stealth/ox-alpha on August 20, 2026. Within 48 hours, independent testing reported 80% Pass@1 on DeepSWE against 65% for Claude Fable 5 and 52% for GPT-5.6 Sol. That spread — beating a frontier model by 28 points, for free — is what drove the coverage.

Then the same tester ran the complete DeepSWE set. Ox Alpha came out roughly level with GPT-5.6 Sol mid. Separately, the LLM Coding Leaderboard evaluated it through OpenCode on August 23 and placed it #26 with 8.9 of 20 points at medium effort.

Two lessons that generalize past this model:

Partial benchmark subsets systematically flatter new models. The subset is usually the tasks the tester ran first, not a random sample.
Corrections do not travel. The 80% figure is still the top search result; the parity result is in one article.

If you are choosing a coding model on the strength of a number published in the same week the model appeared, you are choosing on noise.

Price: Sol Now Undercuts Opus 5

The genuinely actionable change this week was not the stealth model. On August 21, 2026, OpenAI cut GPT-5.6 Sol from $5/$30 to $4/$20 per million tokens — a 20% input cut and a 33% output cut, reported as a promotional window rather than a permanent reprice.

That inverts the frontier price order:

GPT-5.6 Sol: ~$0.22 per 30K-in/5K-out task
Claude Opus 5: ~$0.275 per equivalent task

Sol is now roughly 20% cheaper per task than Opus 5, having been ~9% more expensive before the cut. For a team running millions of agentic coding calls, that is a real line item — with the caveat that promotional pricing can expire, and rebuilding around a temporary rate is how teams end up with a surprise invoice in Q4.

Where Each One Actually Wins

Claude Opus 5 remains the default for long-horizon agentic coding: multi-file refactors, tasks where the model must hold a large codebase in context and make consistent decisions across dozens of steps. Its 1M context and 128K max output are built for that shape of work, and its lead is largest on the hardest tasks rather than on short completions.

GPT-5.6 Sol is now the value pick at the frontier tier. Post-cut it is cheaper than Opus 5 while sitting in the same capability band, and the ecosystem around it is broad — the GPT-5.6 family shipped into AWS’s Kiro agent on August 24, 2026, alongside existing integrations across most major coding surfaces.

Ox Alpha wins exactly one scenario: you want to feel out a 1M-context multimodal model on a public repository for an afternoon at zero cost. That is a legitimate use. It is not a migration.

The Disqualifier

Score aside, Ox Alpha fails the questions that actually gate a production model:

Who operates it? Unknown.
Are prompts retained? Undisclosed.
Are prompts used for training? Undisclosed.
What jurisdiction governs the data? Unknown.
Will it exist next month? No commitment.

A free frontier endpoint from an unnamed operator is most plausibly buying evaluation data with inference cost. That is a fair trade for public code and an unacceptable one for a private codebase. You cannot sign a DPA with a codename.

If You Want Cheap, Buy Cheap Properly

Teams reaching for a free stealth model to cut costs are usually solving the wrong problem. Named alternatives with real contracts, verified August 2026:

Model	Input / Output per MTok	30K/5K task
Grok 4.6	$2 / $6	~$0.09
Gemini 3.7 Flash	$0.75 / $3.75	~$0.041
GLM-5.3	$1.40 / $4.40	~$0.064
Claude Sonnet 5	$2 / $10	~$0.11

Gemini 3.7 Flash costs about 19% of a Sol call and comes with a named provider, published terms and an SLA. If price is the constraint, that is the answer — not an anonymous endpoint.