Cron Explainer Template
- Next.js
- TypeScript
Type a cron expression and read it in plain English, with the next five times it will run.
A Next.js app that explains cron schedules. Type any 5- or 6-field cron expression, or pick a common one, and get a plain-English sentence, each field labelled, and the next five run times with how far away they are. Use it to check a schedule before you deploy it, or lift the route to describe jobs in your own dashboard.
What it does
- Plain English
- Turns an expression like 0 9 * * 1-5 into a sentence: at 9:00 AM on Monday through Friday.
- Next five runs
- Lists when the schedule fires next, in UTC, with how long until each run.
- Fields labelled
- Shows which part of the expression is the minute, hour, day, month and weekday, including the seconds field.
- Shareable links
- Open the app with ?expression= in the URL to explain a schedule straight away, handy in docs and code reviews.
- Keeps your key private
- The browser only talks to your own API route, which checks the field count, holds the key and rate-limits visitors.
How it works
The route: check the field count, answer from the cache, then call Cron Parser.
export async function GET(request: Request) {
const expression = str(new URL(request.url).searchParams.get('expression'), 120).replace(/\s+/g, ' ');
if (!expression) return fail('Enter a cron expression, like 0 9 * * 1-5');
const parts = expression.split(' ').length;
if (parts < 5 || parts > 6) return fail('A cron expression has 5 fields (or 6 with seconds), separated by spaces');
const key = `cron:${expression}`;
const hit = fromCache(key, TTL_MS);
if (hit) return Response.json(hit);
const blocked = guard(request);
if (blocked) return blocked;
return respond(async () => {
const data = await callApi('cronparser', { query: { expression } });
toCache(key, data);
return data;
});
}Deploy it
- Get a free API key
The free plan includes 200 credits a month, no card needed. Create your key.
- Deploy it
Click Deploy to Vercel. Vercel copies the repo to your GitHub account and asks for
APIVERVE_API_KEY: paste your key there. - Open your app
Vercel builds it and gives you a live URL, usually in about a minute. Every push to the repo redeploys it.
Try the Cron Expression Parser API — the call this template makes
No key required to try it. Get a key to use it in your app.
{
"status": "ok",
"error": null,
"data": {
"expression": "0 9 * * 1-5",
"isValid": true,
"format": "5-field",
"fields": {
"second": {
"expression": "0",
"description": "At 0",
"values": [
0
]
},
"minute": {
"expression": "0",
"description": "At 0",
"values": [
0
]
},
"hour": {
"expression": "9",
"description": "At 9",
"values": [
9
]
},
"dayOfMonth": {
"expression": "*",
"description": "Every",
"values": [
1,
2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12,
13,
14,
15,
16,
17,
18,
19,
20,
21,
22,
23,
24,
25,
26,
27,
28,
29,
30,
31
]
},
"month": {
"expression": "*",
"description": "Every",
"values": [
1,
2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12
]
},
"dayOfWeek": {
"expression": "1-5",
"description": "From 1 to 5",
"values": [
1,
2,
3,
4,
5
]
}
},
"description": "At 9:00 AM on Monday, Tuesday, Wednesday, Thursday, Friday",
"frequency": {
"type": "Daily",
"interval": "day"
},
"nextRuns": [
"2026-09-21T09:00:00.000Z",
"2026-09-22T09:00:00.000Z",
"2026-09-23T09:00:00.000Z",
"2026-09-24T09:00:00.000Z",
"2026-09-25T09:00:00.000Z"
]
}
}