| arcsecond.io | Access multiple astronomy data sources and celestial catalogs | No | ✓ | ? | |
| arXiv | Open access repository for research papers in physics, math, and related disciplines | No | ✓ | ? | |
| CORE | Global access to open access research papers and academic publications | apiKey | ✓ | ? | |
| GBIF | Global Biodiversity Information Facility API providing species occurrence data | No | ✓ | ✓ | |
| iDigBio | Access millions of natural history specimen records from museums worldwide | No | ✓ | ? | |
| inspirehep.net | Information system for high energy physics literature and research data | No | ✓ | ? | |
| isEven (humor) | Fun API to check if a number is even | No | ✓ | ? | |
| ISRO | Retrieve public information about Indian Space Research Organization missions | No | ✓ | ✗ | |
| ITIS | Integrated Taxonomic Information System for species classification data | No | ✓ | ? | |
| Launch Library 2 | Database of spaceflight launches, agencies, and events | No | ✓ | ✓ | |
| Materials Platform for Data Science | Curated experimental data and materials properties database | apiKey | ✓ | ✗ | |
| Minor Planet Center | Astronomical data about asteroids and other small Solar System bodies | No | ✗ | ? | |
| NASA | Access NASA’s public data including imagery, astronomy, and satellite data | No | ✓ | ✗ | |
| NASA ADS | NASA Astrophysics Data System for scientific publications and research data | OAuth | ✓ | ✓ | |
| Newton | Perform symbolic and arithmetic mathematical calculations via API | No | ✓ | ✗ | |
| Noctua | Access astronomical data and star catalogues via NoctuaSky API | No | ✓ | ? | |
| Numbers (Math.tools) | Retrieve facts, properties, and trivia about numbers | apiKey | ✓ | ✗ | |
| Numbers API | Simple API providing random or specific facts about numbers | No | ✗ | ✗ | |
| Ocean Facts | Scientific facts and information related to oceanography | No | ✓ | ? | |
| Open Notify | Public data about ISS location, astronauts, and space activity | No | ✗ | ✗ | |
| Open Science Framework | Repository for sharing and archiving open research projects and data | No | ✓ | ? | |
| Purple Air | Real-time air quality monitoring data from sensors around the world | No | ✓ | ? | |
| Remote Calc | Solve remote math calculations using base64-encoded data input | No | ✓ | ✓ | |
| SHARE | Free open dataset about global research and scholarly activity | No | ✓ | ✗ | |
| SpaceX (REST) | Public REST API providing data on SpaceX launches, rockets, and missions | No | ✓ | ✗ | |
| SpaceX (GraphQL) | GraphQL API for querying SpaceX data on launches and vehicles | No | ✓ | ? | |
| Sunrise and Sunset | Calculate sunrise and sunset times for any geographic coordinates | No | ✓ | ✗ | |
| Times Adder | Add multiple time values and return the cumulative result as JSON | No | ✓ | ✗ | |
| TLE | Retrieve Two-Line Element (TLE) satellite orbit data | No | ✓ | ✗ | |
| USGS Earthquake Hazards Program | Real-time earthquake data and seismic event information | No | ✓ | ✗ | |
| USGS Water Services | Retrieve data on water quality and levels for rivers and lakes | No | ✓ | ✗ | |
| World Bank | Access global economic, demographic, and development data | No | ✓ | ✗ | |
| xMath | Generate and solve random mathematical expressions | No | ✓ | ✓ | |