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  5. Mercury 2vsSolar Pro 4
Updated Aug 2026

Mercury 2vsSolar Pro 4

Solar Pro 4 is cheaper than Mercury 2 at $0.09/M vs $0.25/M input tokens.

Mercury 2 and Solar Pro 4 compared across 14 shared prompts
SpecMercury 2Solar Pro 4
Input price$0.25/M tokens$0.09/M tokens
Output price$0.75/M tokens$0.36/M tokens
Context window128K tokens524K tokens
Free API (OpenRouter)NoNo
ReleasedMar 2026Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 14 prompts both answered. Formatting stripped, words untouched.

Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Mercury 21,934 words
Goal: Protect patients, meet legal/ethical obligations, preserve the company’s long‑term credibility, and manage the immediate financial and reputational fallout. Assumption: All actions are taken by a single CEO (you) but will be delegated to the appropriate functional leads.
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Solar Pro 41,851 words
As CEO, my overriding duty is to balance patient safety, legal/regulatory compliance, fiduciary responsibility, and long-term corporate survival. A 1-in-8,000 risk of liver failure is rare but severe, potentially fatal, and materially unexpected relative to the current label.
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Mercury 22,132 words
Below is a clause‑by‑clause risk‑assessment of the sample “Software Consulting Agreement” together with practical revision language that a contractor (or the contractor’s counsel) could propose. The analysis is framed as general information about typical U.S.
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Solar Pro 41,382 words
Disclaimer: I am an AI assistant and not an attorney. The following analysis is for informational purposes only and does not constitute legal advice. Contract laws vary significantly by jurisdiction (e.g., state, country).
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Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Mercury 2291 words
Golden‑Crunch Oatmeal Squares A sweet, chewy snack that comes together with just seven pantry staples. Ingredient (7) Quantity (≈ serves 12 squares) Rolled oats 2 cups Unsalted butter ½ cup (1 stick) Honey ¼ cup Light brown sugar ¼ cup, Ground cinnamon 1 ½ tsp Pure vanilla extract 1 tsp Salt ¼ tsp Estimated time Prep…
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Solar Pro 4294 words
🍝 Golden Umami Silk Noodles A savory-sweet pasta dish that transforms basic pantry staples into a glossy, flavorful meal. It's quick, comforting, and relies on the balance of soy, honey, and butter for a rich sauce without needing fresh produce.
Read the full answer

Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Mercury 22,072 words
Below is a structured “failure‑mode → mitigation” map for the architecture you described. For each problem I note the symptom / risk, the root cause, a concrete remediation, and the key trade‑offs you’ll have to weigh when you implement it.
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Solar Pro 41,598 words
This architecture contains several fundamental mismatches between real-time collaborative editing requirements and the chosen patterns. Below is a systematic breakdown of failure modes, race conditions, and scaling bottlenecks, each with a targeted solution and explicit trade-offs.
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Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Mercury 22,965 words
Executive summary If a practical point‑contact transistor had been demonstrated in 1920 (instead of 1947) the whole post‑World‑War‑II technological trajectory would have been compressed by roughly 15‑20 years.
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Solar Pro 41,638 words
The Premise: The 1920 Solid-State Breakthrough For this scenario to function, we must assume a functional point-contact or junction transistor is demonstrated in 1920 (perhaps by Lilienfeld or an early Bell Labs precursor), and crucially, that methods for purifying semiconductor materials (germanium/silicon) are solved…
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Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

Mercury 21,211 words
Internal Investment Committee Memo – LedgerLift (LLLT) Date: 5 Mar 2026 Recommendation Rating: Long 12‑month price target range: $35 – $55 (mid‑point ≈ $45) Thesis (2 sentences): LedgerLift is benefitting from secular demand for B2B spend‑management SaaS and shows a high‑quality subscription base (NRR 123 % and gross…
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Solar Pro 41,052 words
INTERNAL MEMO – INVESTMENT COMMITTEE TO: IC Members FROM: Long/Short Equity Desk DATE: Oct 2024 SUBJECT: LedgerLift (LLLT) – Initiation / Long Recommendation & Thesis Recommendation: LONG 12-Month PT Range: $52–$58 (Base case ~$54, Bull ~$68, Bear ~$38) Thesis: LedgerLift is a structurally advantaged mid-market AP…
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Our Verdict
Solar Pro 4
Solar Pro 4
Mercury 2
Mercury 2Runner-up

Not enough votes to call it. On the specs, Solar Pro 4 has the edge: bigger model tier, newer, bigger context window.

Slight edge
API pricing

Cost per 1M tokens

Mercury 2
Input
$0.25
Output
$0.75
Solar Pro 4
Input
$0.09
2.8× cheaper
Output
$0.36
2.1× cheaper

Solar Pro 4 is cheaper on both: 2.8× input, 2.1× output.

Where to run it

2 hosts

Mercury 21 host
HostInOutContextUptime
Inception$0.25 in·$0.75 out·128k·100% up
Solar Pro 41 host
HostInOutContextUptime
UUpstage$0.09 in·$0.36 out·524k·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 22 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Mercury 2 is developed by Inception while Solar Pro 4 is developed by Upstage. Mercury 2 has a 128K token context window vs Solar Pro 4's 524K. You can compare their actual outputs across 14 challenges on Rival to see how they differ in practice.

It depends on your use case. Mercury 2 and Solar Pro 4 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 14 challenges so you can judge which fits your needs best.

Mercury 2 costs $0.25/M input tokens and Solar Pro 4 costs $0.09/M input tokens. Solar Pro 4 is $0.16/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Mercury 2 and Solar Pro 4 across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Rival
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Explore all of Rival

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