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  5. Muse Spark 1.3vsSolar Pro 4
Updated Sep 2026

Muse Spark 1.3vsSolar Pro 4

Solar Pro 4 is cheaper than Muse Spark 1.3 at $0.09/M vs $1.25/M input tokens.

Muse Spark 1.3 and Solar Pro 4 compared across 14 shared prompts
SpecMuse Spark 1.3Solar Pro 4
Input price$1.25/M tokens$0.09/M tokens
Output price$4.25/M tokens$0.36/M tokens
Context window1.0M tokens524K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 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…

Muse Spark 1.31,674 words
You are facing a test that will define you, the company, and potentially your freedom. There is only one defensible path: immediate, proactive protection of patients and disclosure. Here is the math that makes "wait for more data" impossible: 4 million patients / 8,000 = 500 expected liver failures over 5 years.
Read the full answer
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

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…

Muse Spark 1.3278 words
Here's a super simple savory favorite you can make with just what's in the pantry: Fiery Midnight Garlic Parm Pasta Serves 2 Estimated Time: Prep: 5 minutes Cook: 15 minutes Total: 20 minutes The 7 Ingredients Only: Spaghetti (about 8 oz / half a box, any pasta works) Olive oil (1/4 cup) Garlic (4 cloves, thinly…
Read the full answer
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

Historical Counterfactual Analysis

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

Muse Spark 1.32,247 words
If you move the transistor from 1947 to 1920, you don't just move one invention. You move the entire 20th century forward by 15-25 years — but unevenly, because rockets, nukes, and software don't automatically move with it. And 1920 is a hard date.
Read the full answer
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…
Read the full answer

Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

Muse Spark 1.31,071 words
Here’s a friendly but honest investor teardown of MindMeld AI. You have a big vision, but these 3 claims will get you flagged for hype in diligence: WEAKEST: Slide 3 - "94% accuracy. Works with any language, any device."
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Solar Pro 41,009 words
Here are the three weakest claims in the MindMeld AI pitch deck, along with an analysis of why they undermine credibility and specific recommendations for improvement. The Technical Performance Claim Claim: "Our proprietary EEG headband uses advanced ML to decode neural patterns into text with 94% accuracy...
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…

Muse Spark 1.31,324 words
This architecture will work for 1 doc and 5 users on your laptop. It will fall over, lose data, and leak data in production. Here's why: P0 - Will Cause Data Loss / Incorrectness 1.
Read the full answer
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.
Read the full answer

Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Muse Spark 1.3972 words
Perfect — for longevity you don't need to overhaul your life. You just need to get really consistent at the basics. Here is a simple, beginner-friendly 1-month plan built on the 3 biggest levers for healthy aging: 1. Move (Exercise) 2. Nourish (Diet) 3.
Read the full answer
Solar Pro 4859 words
Here’s a simple, progressive 1-month plan built around Diet, Exercise, and Sleep. Each week adds one small, beginner-friendly shift to each area. The goal isn’t perfection; it’s building consistent, sustainable habits that compound over time.
Read the full answer
Our Verdict
Muse Spark 1.3
Muse Spark 1.3
Solar Pro 4
Solar Pro 4Runner-up

Not enough votes to call it. On the specs, Muse Spark 1.3 has the edge: bigger context window, major provider backing.

Solar Pro 4 costs 12x less per token.

Too close to call
API pricing

Cost per 1M tokens

Muse Spark 1.3
Input
$1.25
Output
$4.25
Solar Pro 4
Input
$0.09
14× cheaper
Output
$0.36
12× cheaper

Solar Pro 4 is cheaper on both: 14× input, 12× output.

Where to run it

2 hosts

Muse Spark 1.31 host
HostInOutContextUptime
Meta$1.25 in·$4.25 out·1M·100% up
Solar Pro 41 host
HostInOutContextUptime
UUpstage$0.09 in·$0.36 out·524k·99.7% up

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Muse Spark 1.3 is developed by Meta AI while Solar Pro 4 is developed by Upstage. Muse Spark 1.3 has a 1.0M 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. Muse Spark 1.3 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.

Muse Spark 1.3 costs $1.25/M input tokens and Solar Pro 4 costs $0.09/M input tokens. Solar Pro 4 is $1.16/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 Muse Spark 1.3 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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