Julian Day Calculator converts between Gregorian calendar dates and Julian Day Numbers (JDN). Julian Day is a continuous count of days used in astronomy and historical research.
Try it — live request, no key required
GETapi.apiverve.com/v1/julianday
VerificationFormat
No key required to try it. Get a key to use it in your app.
{
"status": "ok",
"error": null,
"data": {
// Julian Day Calculator response payload
}
}Code examples — ready to paste, with real parameters
curl "https://api.apiverve.com/v1/julianday?date=2024-03-15" \
-H "x-api-key: YOUR_API_KEY"Replace
YOUR_API_KEY with your key.Full reference in the docs →
Access methods
Call it however you build.
One endpoint, many ways in — REST with JSON, XML, YAML, and CSV, plus GraphQL and an MCP interface for AI agents.
JSON
Default REST response
XML
Markup format
YAML
Human-readable
CSV
Tabular export
Beta
GraphQL
Query language
New
MCP
For AI agents
Zero-code embed
Drop it into any site.
Add an interactive form for Julian Day Calculator with a single snippet — no backend, no keys in your markup.
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What does the Julian Day Calculator API do?
Julian Day Calculator converts between Gregorian calendar dates and Julian Day Numbers (JDN). Julian Day is a continuous count of days used in astronomy and historical research.
How do I authenticate Julian Day Calculator API requests?
Pass your API key in the x-api-key header over HTTPS. One key works across all 300+ APIVerve APIs — there are no per-endpoint credentials.
How much does the Julian Day Calculator API cost?
Each call spends 1 credit from your shared pool. The free tier includes 100 credits every month, and paid plans add more headroom.
How fast is the Julian Day Calculator API?
Typical responses return in around 186 ms (p50), served from 24 regions under a 99.9% uptime SLA.
What response formats does the Julian Day Calculator API support?
JSON by default, plus XML and YAML via the format parameter. GraphQL and an MCP interface for AI agents are available across the catalog.
What HTTP method does the Julian Day Calculator API use?
GET over HTTPS, following standard REST conventions with a consistent { status, error, data } response envelope.