NASA vs Newton

NASA's Open APIs give programmatic access to imagery and data from missions across the agency — the Astronomy Picture of the Day, Mars rover photos, near-Earth object tracking, and Earth-imagery archives among them. A free registered key raises the shared DEMO_KEY's 30-requests/hour limit to 1,000 requests/hour. All endpoints return JSON.

Newton is a keyless calculator API deployed as a Vercel serverless function: the operation (simplify, factor, derive, integrate, and more) and expression are both encoded directly in the URL path, and it answers with a small JSON object containing the result. It's a solo open-source project (aunyks/newton-api) rather than a commercial service, so there's no pricing tier or rate limit to opt into.