AI Model Comparison
Side-by-side comparison of pricing, context window, benchmarks, capabilities, and license. Every figure comes from the developer's own pages, last checked on ; each model's page lists its sources. A figure we could not source shows as a dash.
Model A — SK Telecom
A.X K2 is a foundation model from SK Telecom, released on July 29, 2026, built under the Korean government’s Sovereign AI foundation model project and trained from scratch in FP8. SK Telecom says it succeeds the 519B-parameter A.X K1 with stronger math, science, Korean-language and long-context reasoning.
Model B — Upstage
Solar Pro 4 is Upstage’s flagship model, released on August 6, 2026, built for agentic use and document-based work, coding and business tasks. It supports a 512K context, up to 128K output tokens and a reasoning mode. It is available through Upstage’s console and on-premises.
| Property | A.X K2 | Solar Pro 4 |
|---|---|---|
| Released | Jul 29, 2026 | Aug 6, 2026 |
| Developer | SK Telecom | Upstage |
| Type | llm | llm |
| License | open-weight | proprietary |
| Context window | 262,144 | — |
| Parameters | 688B total, 33B active (Mixture of Experts) | — |
| Developer status | — | — |
| Input $/M tokens | — | $0.15 |
| Output $/M tokens | — | $0.60 |
Bold green values indicate the winner on that dimension where comparison is meaningful (lower price wins; bigger context wins; more open license wins; newer date wins). Prices are the ones each developer lists today; a model it no longer prices has none.
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Programmatic access available at /api/ai/compare?a=ax-k2&b=solar-pro-4. CORS is open. Citation guidance: /about/editorial-process.