Science & Space APIs
Free science and space APIs with verified examples: NASA imagery, ISS tracking, live earthquake feeds, rocket launches and Wikipedia summaries. Mostly key-free.
61 tested APIs with full docs · 57 need no key · 40 more listed
Tested, with full documentation
We called each of these before publishing. Every page carries a working curl command, the real JSON response it returned, parameters and common errors.
AlphaFold DB
Free AlphaFold Protein Structure Database API with no key. Fetch predicted 3D structures, per-residue confidence and PDB/mmCIF download links by UniProt accession. Tested example included.
Verified 21 Aug 2026
Arcsecond.io
Free Arcsecond.io objects API with no key: resolve an astronomical object name to coordinates in four systems, plus aliases, spectral type and physical parameters.
Verified 21 Aug 2026
arXiv
Free arXiv API with no key: search 2M+ preprints across physics, mathematics, computer science and biology, with abstracts, authors and PDF links. Tested.
Verified 20 Aug 2026
NCI CACTUS Resolver
Free NCI CACTUS Chemical Identifier Resolver with no key: convert any chemical name, CAS number, InChI or SMILES into any other representation. One URL, plain text response.
Verified 21 Aug 2026
CelesTrak
Free CelesTrak GP API with no key: current orbital elements for every tracked satellite as TLE, JSON, CSV, XML or KVN. Query by NORAD id, name, group or launch designator.
Verified 21 Aug 2026
CERN Open Data
Free CERN Open Data Portal API with no key: search and retrieve records for LHC datasets, software, configuration files and documentation from CMS, ATLAS, LHCb and ALICE.
Verified 21 Aug 2026
ChecklistBank
Free ChecklistBank API with no key: search the Catalogue of Life and thousands of taxonomic checklists by name, with full classification, synonyms and nomenclatural status.
Verified 21 Aug 2026
ChEMBL
Free ChEMBL REST API with no key: 2.4 million drug-like compounds with structures, calculated properties, bioactivity measurements and clinical development phase. Tested example included.
Verified 21 Aug 2026
Crossref
Free Crossref API with no key: 160M+ scholarly works with DOIs, authors, journals, citations and funding data. The backbone of academic metadata. Tested.
Verified 20 Aug 2026
Crystallography Open Database
Free Crystallography Open Database API with no key: search half a million published crystal structures by text, formula, cell parameters or space group. CIF downloads included.
Verified 21 Aug 2026
DataCite
Free DataCite API with no key: DOI metadata for research datasets, software and preprints, complementing Crossref's journal coverage. Tested example.
Verified 20 Aug 2026
DOAJ
Free DOAJ API with no key: search 600,000+ open access articles and 20,000+ vetted open access journals with licence and APC data. Tested curl example.
Verified 20 Aug 2026
EMBL-EBI OLS4
Free EMBL-EBI Ontology Lookup Service (OLS4) API with no key. Search and resolve terms across GO, EFO, MONDO, ChEBI, UBERON and 250+ biomedical ontologies. Tested example included.
Verified 21 Aug 2026
EMSC Seismic Portal
Free EMSC Seismic Portal FDSN API with no key: real-time earthquake events worldwide as GeoJSON, with magnitude, depth, region and contributing agency. Tested example included.
Verified 21 Aug 2026
Encyclopedia of Life
Free Encyclopedia of Life API with no key: species pages aggregating names, classifications, traits and media from hundreds of contributing databases and museums.
Verified 21 Aug 2026
Ensembl REST
Free Ensembl REST API with no key: genome assemblies, gene and transcript lookups, sequences, variants and cross-species comparative genomics. Tested example included.
Verified 21 Aug 2026
Europe PMC
Free Europe PMC API with no key: search 40M+ life science publications and abstracts, with full text where open access, citations and preprints. Tested.
Verified 20 Aug 2026
GeoNet New Zealand
Free GeoNet API with no key: New Zealand earthquakes with Modified Mercalli intensity, volcanic alert levels, strong-motion data and network station metadata as GeoJSON.
Verified 21 Aug 2026
gnomAD
Free gnomAD GraphQL API with no key: population allele frequencies, variant constraint and gene data from 800,000+ exomes and genomes. Tested POST example and live response.
Verified 21 Aug 2026
Human Protein Atlas
Free Human Protein Atlas search API with no key: tissue, cell-line, pathology and subcellular protein expression data as JSON, TSV or XML. Column selection included. Tested example.
Verified 21 Aug 2026
iDigBio
Free iDigBio search API with no key: query 140M+ digitised museum specimen records in Darwin Core, with locality, collector, date and media. Tested example included.
Verified 21 Aug 2026
INSPIRE-HEP
Free INSPIRE-HEP API with no key: search high-energy physics papers, authors, conferences and institutions, with BibTeX and LaTeX export built in. Tested example included.
Verified 21 Aug 2026
InterPro
Free InterPro REST API with no key: protein families, domains and functional sites integrated from Pfam, PROSITE, SMART, CDD and 10 other member databases. Tested example included.
Verified 21 Aug 2026
ISRO API
Free community ISRO API with no key: lists of Indian spacecraft, launchers, centres and customer satellites as simple JSON. No account, no rate limit, tiny responses.
Verified 21 Aug 2026
Open Notify ISS
Free API returning the International Space Station's live latitude and longitude. No key, updates in real time. Tested curl example and live JSON response.
Verified 19 Aug 2026
JPL Horizons
Free NASA JPL Horizons API with no key: compute high-precision ephemerides, positions, velocities and physical data for planets, moons, asteroids, comets and spacecraft.
Verified 21 Aug 2026
JPL Small-Body Database
Free NASA JPL Small-Body Database API with no key: orbital elements, physical parameters, discovery data and close-approach records for every known asteroid and comet.
Verified 21 Aug 2026
KEGG REST
Free KEGG REST API with no key: metabolic pathways, genes, compounds, drugs and reactions across thousands of organisms. Returns tab-separated plain text. Tested example included.
Verified 21 Aug 2026
Launch Library 2
Free rocket launch API with no key: upcoming and past launches from every space agency, with rockets, missions, pads and live stream links. Tested example.
Verified 19 Aug 2026
MyGene.info
Free MyGene.info API with no key: query gene annotation aggregated from NCBI, Ensembl, UniProt and more by symbol, Entrez id or Ensembl id. Field selection keeps responses small.
Verified 21 Aug 2026
NASA APOD
Free NASA Astronomy Picture of the Day API. Daily space images with expert explanations, HD URLs and archive access back to 1995. Tested curl example.
Verified 19 Aug 2026
NASA NeoWs (Asteroids)
Free NASA asteroid API: near-Earth objects by date with size, velocity, miss distance and hazard classification. Works with DEMO_KEY. Tested example.
Verified 20 Aug 2026
NASA EPIC
Free NASA EPIC API: full-disc Earth photographs taken daily from the DSCOVR satellite a million miles away, with coordinates and metadata. Tested example.
Verified 20 Aug 2026
NASA Exoplanet Archive
Free NASA Exoplanet Archive TAP API with no key: query 5,000+ confirmed exoplanets and their host stars with SQL-like ADQL, returning JSON, CSV or VOTable.
Verified 21 Aug 2026
NASA Image and Video Library
Free NASA Image and Video Library API with no key: search 140,000+ NASA photos, videos and audio with captions, keywords and multiple resolutions. No account needed.
Verified 21 Aug 2026
NASA DONKI
Free NASA space weather API: solar flares, coronal mass ejections, geomagnetic storms and radiation belt events with impact analysis. DEMO_KEY works. Tested.
Verified 20 Aug 2026
NASA TechPort
Free NASA TechPort API with no key: metadata for thousands of NASA technology development projects, including descriptions, taxonomy, funding and responsible centres.
Verified 21 Aug 2026
NCBI Datasets
Free NCBI Datasets v2 API with no key. Query genome assemblies, gene and taxonomy metadata for any organism and build download packages. Tested curl example and live response.
Verified 21 Aug 2026
Newton Math API
Free Newton maths API with no key: differentiate, integrate, simplify, factor, find zeroes and more from a plain URL. No account, tiny JSON responses, CORS enabled.
Verified 21 Aug 2026
NIH RePORTER
Free NIH RePORTER API with no key: search every NIH-funded research project by year, institution, investigator, funding amount and topic. POST-based query API. Tested example included.
Verified 21 Aug 2026
NOAA Space Weather Prediction Center
Free NOAA Space Weather Prediction Center API with no key: geomagnetic storm alerts, solar flare warnings, Kp index, solar wind and aurora forecasts as JSON products.
Verified 21 Aug 2026
Nobel Prize
Official Nobel Prize API with no key: every prize and laureate since 1901 with categories, motivations, affiliations and biographical data. Tested examples.
Verified 20 Aug 2026
Open Targets Platform
Free Open Targets GraphQL API with no key: gene-disease associations, evidence scores, known drugs and tractability data for drug target identification. Tested example included.
Verified 21 Aug 2026
Open Tree of Life
Free Open Tree of Life API with no key: match scientific names to taxonomy identifiers, resolve synonyms and fetch subtrees of the synthetic tree of life. Tested POST example included.
Verified 21 Aug 2026
OpenAIRE
Free OpenAIRE Search API with no key: publications, datasets, software and projects linked to EU funding, harvested from thousands of repositories. Tested example included.
Verified 21 Aug 2026
OpenAlex
Free OpenAlex API with no key: 250M+ scholarly works, authors, institutions, topics and citation graph. The open replacement for Microsoft Academic. Tested.
Verified 20 Aug 2026
OpenCitations
Free OpenCitations API with no key: open citation data linking DOIs — who cites whom, with timespans. An open alternative to proprietary citation indexes. Tested.
Verified 20 Aug 2026
OPSIN
Free OPSIN web service at EMBL-EBI with no key: parse systematic IUPAC chemical names into SMILES, InChI or CML algorithmically. Open source, deterministic, no lookup table.
Verified 21 Aug 2026
ORCID
Free ORCID public API with no key: researcher profiles, publications, affiliations and funding by persistent researcher identifier. Tested curl example.
Verified 20 Aug 2026
Open Science Framework
Free Open Science Framework API with no key for public data: projects, registrations, preprints, files and contributors in JSON:API format. Tested example and live response.
Verified 21 Aug 2026
RCSB PDB
Free RCSB Protein Data Bank API with no key: experimental metadata, citations, resolution and assembly details for every deposited 3D macromolecular structure. Tested example included.
Verified 21 Aug 2026
Reactome ContentService
Free Reactome ContentService API with no key: query curated biological pathways, reactions, participants and cross-references. CC0 licensed. Tested example and live response included.
Verified 21 Aug 2026
SIMBAD
Free SIMBAD TAP API from CDS with no key: query 13 million astronomical objects with ADQL, returning identifiers, coordinates, object types, magnitudes and bibliography.
Verified 21 Aug 2026
STRING
Free STRING database API with no key: protein-protein interaction networks with per-evidence confidence scores for 12,000+ organisms. Tested curl example and live response included.
Verified 21 Aug 2026
TLE API
Free TLE API with no key: search 20,000+ tracked satellites by name and fetch current two-line element sets as JSON-LD. Simple search endpoint, no account required.
Verified 21 Aug 2026
UniProt
Free UniProt REST API with no key: protein sequences, functions, structures and cross-references for every known protein. Field selection keeps responses small. Tested example included.
Verified 21 Aug 2026
Unpaywall
Free Unpaywall API with no key: find legal open-access versions of paywalled papers by DOI, with direct PDF links and licence information. Tested example.
Verified 20 Aug 2026
USGS Earthquake
Free USGS earthquake API with no key: live global seismic events as GeoJSON, filterable by magnitude, time and location. Tested curl example and live response.
Verified 19 Aug 2026
Where the ISS at?
Free ISS tracking API with no key: live position, altitude, velocity, footprint and solar position, plus TLE orbital elements and future position prediction. Tested.
Verified 20 Aug 2026
Wikipedia REST API
Free Wikipedia REST API with no key: article summaries, extracts, thumbnails and full content in 300+ languages. CORS enabled. Tested curl example.
Verified 19 Aug 2026
Zenodo
Free Zenodo API with no key for reads: search millions of research datasets, papers, software and figures from CERN's open repository with DOIs. Tested.
Verified 20 Aug 2026
Choosing between these Science & Space APIs
Science APIs are among the most genuinely valuable free data sources on the internet, because many are run by public institutions with a mandate to publish. USGS earthquake data and NASA's imagery endpoints are open government data, not free tiers that might disappear.
NASA's API accepts the shared key DEMO_KEY for casual testing, which is what the verified example on that page uses — but that key is heavily rate-limited across all users, so register your own free key before shipping anything.
More Science & Space APIs in the directory
40 further APIs in this category, of which 32 need no API key. These are catalogued from the public-API lists and link straight to each provider's own documentation — we have not tested them yet, so treat the auth and CORS flags as the upstream list's claim rather than ours. They are promoted to a full tested page as we work through them.
| API | What it does | Auth |
|---|---|---|
| Bootprint | Random facts and images of space | NoneCORS |
| CodeCogs | Render LaTeX equations in PNG, GIF, SVG, EMF, PDF, JSON, or download formats with styling options | None |
| CORE | Access the world's Open Access research papers | Key |
| CycleCalcs | Interpreted astronomy: sun and moon times, moon phases, planets, eclipses, seasons | NoneCORS |
| EPO | European patent search system api | OAuth |
| GBIF | Global Biodiversity Information Facility | NoneCORS |
| inspirehep.net | High Energy Physics info. system | None |
| isEven (humor) | Check if a number is even | None |
| ISRO | ISRO Space Crafts Information | None |
| ITIS | Integrated Taxonomic Information System | None |
| Materials Platform for Data Science | Curated experimental data for materials science | Key |
| Minor Planet Center | Asterank.com Information | None |
| Moonlora | Moon phases, illumination, moon signs, full/new moon dates (1900–2100), moonrise/moonset by coordinates | NoneCORS |
| NASA | NASA data, including imagery | None |
| NASA ADS | NASA Astrophysics Data System | OAuthCORS |
| Newton | Symbolic and Arithmetic Math Calculator | None |
| Noctua | REST API used to access NoctuaSky features | None |
| Numbers | Number of the day, random number, number facts and anything else you want to do with numbers | Key |
| Numbers | Facts about numbers | None |
| Ocean Facts | Facts pertaining to the physical science of Oceanography | None |
| Open Notify | ISS astronauts, current location, etc | None |
| OrbitalWiki | Catalog of 16,000+ satellites with the source cited for every field: orbital elements, operators, NORAD/COSPAR IDs | KeyCORS |
| PatentsView | API is intended to explore and visualize trends/patterns across the US innovation landscape | None |
| Purple Air | Real Time Air Quality Monitoring | None |
| Remote Calc | Decodes base64 encoding and parses it to return a solution to the calculation in JSON | NoneCORS |
| Satellite Passes | Find satellite passes | NoneCORS |
| SHARE | A free, open, dataset about research and scholarly activities | None |
| SpaceX | Company, vehicle, launchpad and launch data | None |
| SpaceX | GraphQL, Company, Ships, launchpad and launch data | None |
| Sunrise and Sunset | Sunset and sunrise times for a given latitude and longitude | None |
| Tallytopia | Calculators for finance, health, math, space and sports with step-by-step results | NoneCORS |
| Times Adder | With this API you can add each of the times introduced in the array sended | None |
| TIPO | Taiwan patent search system api | Key |
| TLE | Satellite information | None |
| USGS Earthquake Hazards Program | Earthquakes data real-time | None |
| USGS Water Services | Water quality and level info for rivers and lakes | None |
| USPTO | USA patent api services | None |
| VedIntel™ AstroAPI | Vedic astrology computation — birth charts, dashas, panchang, AI narratives | KeyCORS |
| World Bank | World Data | None |
| xMath | Random mathematical expressions | NoneCORS |
Turn API responses into results
Once the request works you still have to do something with what comes back. These run in your browser, free, with nothing uploaded.
JSON Formatter
Paste a raw response and read it indented, folded and colour-coded.
JSON Path Finder
Click any value to get the path that reaches it in your own code.
JSON to TypeScript
Turn a captured response into typed interfaces before you write the fetch.
CSV to JSON Converter
Turn a spreadsheet into the request body a POST endpoint expects.
Unix Timestamp Converter
Decode the epoch fields almost every API returns.
JWT Decoder
Read the claims and expiry inside a bearer token without pasting it anywhere.
PDF Table to CSV
Pull a table out of a PDF so it can be posted to an API as data.
Event Schema Generator
Publish what an API returns as structured data search engines can read.