JSON to ICS Converter
Processing entirely on your device — large files may take a moment.
JSON Data and iCalendar File exist for different jobs: JSON (JavaScript Object Notation) is the data exchange format of the web — human-readable text that APIs, apps and configuration files all speak natively. Flatten ICS to CSV to audit schedules, merge timetables or import into tools without calendar support.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How JSON compares to ICS
| JSON | ICS | |
|---|---|---|
| Structure | Trees of objects and arrays | VEVENT / VTODO blocks |
| Types / schema | Six native types | Dates, durations, text props |
| Compatibility | Universal, machine-first | Google, Outlook, Apple Calendar |
| Best for | APIs, app data, config-as-code | Schedules and event lists |
How to convert JSON to ICS
- 1
Select your files
Drag & drop your JSON files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to ICS". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted ICS file individually, or grab everything at once as a ZIP archive.
About the JSON format
JSON (RFC 8259, popularized by Douglas Crockford) is the lingua franca of program data. It has exactly six types — string, number, boolean, null, array, object — nested into trees, and every language on earth parses it natively. REST APIs, NoSQL documents, browser configuration, package manifests: if software talks to software, JSON is usually the sentence.
The spec is deliberately strict: double quotes only, no trailing commas, no comments. That rigidity makes parsers trivial and interop reliable, but it also makes JSON awkward for hand-edited config (people bolt comments on and break parsers) and its 1:1 text mapping keeps large files heavier than binary alternatives.
+ Strengths
- ✓Native parsing in every language
- ✓Six clear types, nesting as deep as needed
- ✓The default of APIs and modern tooling
! Limitations
- −No comments — poor fit for hand-edited config
- −Strict syntax: trailing commas and single quotes break it
- −Verbose; large files parse slowly
About the ICS format
ICS is iCalendar (RFC 5545): the text format every calendar system imports and exports. Events carry start/end times, locations, organisers, attendees, alarms and recurrence rules — which makes an .ics attachment a small database of “what happens when”.
Flattening ICS to CSV turns that database into rows: one event per line with columns for time, place and summary — ideal for auditing a shared calendar, merging timetables or feeding a spreadsheet.
+ Strengths
- ✓Universal calendar interchange
- ✓Carries recurrence and alarms
- ✓Plain text, easy to parse
! Limitations
- −Recurring events expand only on export
- −Timezones are easy to get wrong
Why convert JSON to ICS?
There is a concrete reason this conversion exists: No comments — poor fit for hand-edited config ICS sidesteps that — Universal calendar interchange If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this JSON to ICS converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for JSON to ICS?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
How large can my JSON file be?
Since everything runs locally in your browser, the real limit is your device memory rather than an upload cap. Files up to a few hundred megabytes are usually fine on a modern computer; extremely large ones simply take longer.
Are formulas, styles or multiple sheets converted?
No — this conversion extracts the data itself into ICS. Formulas are exported as their current values, styling is not carried over, and multi-sheet workbooks convert sheet by sheet. For full fidelity between spreadsheet formats, exchange within the same tool family.