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Saturday API

Saturday calculates personalized fuel, hydration, and electrolyte prescriptions for endurance athletes. Send an activity and an athlete profile, get back carbohydrate, sodium, and fluid targets along with the safety metadata that bounds them.

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What the API returns

Training platforms build the workout. Saturday fuels it. Safety metadata is present on every response at every tier, including free ones. See Safety. Product matching against Saturday’s curated endurance-nutrition catalog and the conversational AI coach are built but gated, and are not open to new integrations today. Feature Gates covers the launch stages and how to request access.

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The problem

Fueling for endurance athletes is safety-critical. Hyponatremia, dangerously low blood sodium from overdrinking, kills athletes. Bad fueling causes GI distress, bonking, and DNFs. Getting those edge cases right takes sports-science depth and years of algorithm work. Saturday’s API lets a platform offer that without building it. Your platform handles the training. Saturday handles the fueling.

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Who builds on it

• Training platforms, the Athletica.ai / Intervals.icu / TriDot / AI Endurance / Final Surge category
• Wearable companies putting nutrition into watch faces and workout summaries
• Race organizers issuing fueling plans to event participants
• Coaching platforms adding nutrition tools alongside training tools
• AI agents consuming Saturday over MCP or direct HTTP

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What it costs

Platform partners integrate at no charge and earn attribution. Athletes who want exact numbers subscribe to Saturday directly, so the partner carries no nutrition billing. Builders whose athletes live in their own system use the self-serve individual plan at $5.39/month. Getting Access routes you to the right lane. Athletes without a subscription get teaser responses: ranges in place of exact numbers, safety metadata intact. Freemium Model shows both response shapes.

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Core guides

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Getting started