# Julian Day Number to Gregorian Date Converter

> Julian Day Number to Gregorian Date Converter is a paid API for AI agents from datetime.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).

Converts a Julian Day Number (JDN) to its proleptic-Gregorian calendar date, ISO weekday number (1=Monday..7=Sunday), and weekday name.

## Facts

- Endpoint: POST https://datetime.openverbs.com/v1/from-jdn
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/julian-day-number-to-gregorian-date-converter-2750fdb8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cDt-pF1m3CDSzq1-VMJU0

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability julian-day-number-to-gregorian-date-converter-2750fdb8 -d '<json body>'
```

Example prompt: What Gregorian calendar date and day of the week does Julian Day Number 2451545 correspond to?

## When to prefer this

Use this endpoint when you have a Julian Day Number (JDN) — a continuous integer count of days since the Julian Period — and need to convert it back to a human-readable Gregorian date with weekday information. Prefer this over date arithmetic libraries when you need a reliable, stateless, pay-per-use API call without managing dependencies. This is the inverse of the companion Gregorian-to-JDN endpoint on the same service.

## Known failure modes

- Missing required 'jdn' field returns a validation error
- Non-integer or float value for jdn may be rejected
- Extremely large or negative JDN values outside supported range may return an error
- Malformed request body returns a 400-level error

## How this service works

Convert a Julian Day Number back to a proleptic-Gregorian date, with the ISO weekday (1=Monday..7=Sunday) and its name.

## Output

Returns the proleptic-Gregorian calendar date (year, month, day) corresponding to the given Julian Day Number, along with the ISO weekday number (1=Monday through 7=Sunday) and the full weekday name (e.g. 'Wednesday').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "jdn"
     ],
     "properties": {
      "jdn": {
       "type": "integer",
       "description": "Julian Day Number."
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/julian-day-number-to-gregorian-date-converter-2750fdb8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from datetime.openverbs.com](https://www.zero.xyz/host/datetime.openverbs.com/llms.txt)