.ics Validator / Linter

Q: Does the validator change my data?

Validation is read-only until you press Fix Common Issues. When activated, fixes are applied client-side and you can inspect every change before downloading the regenerated feed.

Accelerate calendar QA with instant RFC 5545 checks, guided fixes, and export-ready reporting crafted for SaaS teams, developers, and QA analysts.

Faster than hosted alternatives — all processing happens locally.

Validate your calendar feed

Upload a file or paste raw ICS text, then select Validate to uncover errors, warnings, and quick wins.

Upload .ics file No file selected.

Load or share a state with the permalink button.

0 Events parsed

0 Errors

0 Warnings

0 Safe fixes applied

Line-by-line diagnostics

No diagnostics yet. Validate a calendar feed to populate this view.

About the .ics Validator / Linter

Calendar publishers, SaaS builders, and QA engineers told us that existing .ics checkers feel slow, cryptic, or locked behind support tickets. This tool was engineered to change that. It loads instantly, inspects every line for RFC 5545 compliance, and highlights the human-readable cause alongside remediation guidance. Because everything runs client-side, proprietary feed data never leaves your browser, keeping compliance teams comfortable while your product team iterates quickly.

We benchmarked popular web validators and tuned this experience to be faster, lighter, and more actionable. You get intelligent summaries, timezone reconciliation, RRULE sanity checks, and exportable reports without needing to install anything or open a terminal. Use it as a final QA gate before publishing feeds, or embed it in your internal QA runbooks.

How to Use

Upload an .ics export or paste raw text into the editor, then tap Validate. The parser normalizes line endings, unfolds wrapped lines, and scopes diagnostics to the exact line number that needs attention. Severity badges distinguish must-fix errors from nice-to-fix warnings, so you can triage quickly. Use Fix Common Issues to auto-generate missing UIDs, align DTSTART and DTEND timezones, and inject a compliant PRODID if it is absent. When the feed is clean, download the regenerated file or ship the permalink to teammates.

Need documentation proof? Export the full diagnostics table to CSV for audit trails or copy the human-friendly summary directly to your issue tracker. All actions update in real time, and a live metrics panel tracks events parsed, critical failures, and safe fixes applied.

Tips

Break complex recurring events into smaller test cases to ensure RRULE coverage and avoid unintended multi-year recurrences. Always include a UTC DTSTAMP alongside UID to help calendar clients deduplicate updates. If you serve feeds across regions, rely on IANA timezone IDs rather than numeric offsets so daylight transitions resolve correctly. After auto-fixing, review the diff in your favorite editor before committing to version control. Finally, bookmark the permalink feature to snapshot failing states and collaborate faster with engineering or support teams.

FAQs

Does the validator change my data?

Validation is read-only until you press Fix Common Issues. When activated, fixes are applied client-side and you can inspect every change in the editor before downloading the regenerated feed.

Which RFC checks are covered?

We focus on high-impact RFC 5545 rules: calendar scaffolding, UIDs, timestamps, RRULE syntax, timezone balance, and ASCII conformance. The roadmap includes deeper VALARM and VTODO validation.

Can I share results with stakeholders?

Yes. Generate a shareable permalink for the current state, export diagnostics to CSV, or copy the narrative summary to your clipboard. No server round-trips are required.

Read Also: