Slack Timestamp Formatter

How to use

1. 1Pick the event date and time in the datetime-local input, then select the source time zone the event happens in.
2. 2Optionally use a quick chip (Now, +15 min, +1 hour, +3 hours, Tomorrow same time, +1 week) for fast scheduling, or click Set to now.
3. 3Pick a preset (Date and time, Full event header, Pretty date plus time, ISO date only, Time only, Time with seconds) or build your own token string by clicking token chips like {date_short} or {time}.
4. 4Optionally add a link URL to turn the rendered date into a Slack hyperlink, and edit the fallback text shown in older clients (or leave it blank to auto-use the preview).
5. 5Use Preview as reader in to confirm how a teammate in another zone will see it, then click Copy placeholder and paste it into any Slack message, bot reply, webhook payload, or Block Kit text field.

About this tool

Slack Timestamp Formatter builds the special date and time placeholders Slack expands into the reader's own time zone, locale, and hour-cycle preference inside any chat message, bot reply, webhook payload, or Block Kit field. Slack stores the placeholder in the form <!date^UNIX_SECONDS^TOKEN_STRING^OPTIONAL_URL|FALLBACK>, where the Unix timestamp is the single source of truth, the token string mixes literal text with Slack's date and time tokens, the optional URL turns the rendered text into a hyperlink, and the fallback text covers older mobile clients, plain-text exports, search snippets, and notification previews. The tool exposes every token Slack documents: {date_num} for sortable YYYY-MM-DD output, {date} and {date_short} and {date_long} for prose-style dates from short to weekday-full, the three pretty variants {date_pretty} {date_short_pretty} {date_long_pretty} that swap today, tomorrow, or yesterday in for the nearby days and fall back to the matching format otherwise, plus {time} and {time_secs} for time with or without seconds. A datetime-local input plus an IANA time zone picker convert your wall-clock event time to the right UTC instant, including a two-pass DST correction so the wall clock you typed always re-renders identically in the source zone around spring and fall transitions. The reader-zone selector previews how the same placeholder renders for a teammate elsewhere, and a 12-hour or 24-hour preview toggle mirrors each reader's hour-cycle preference. Quick presets cover the patterns Slack users reach for most: {date_short} at {time} for the everyday case, {date_long} at {time} for event headers, {date_pretty} at {time} for natural-language framing, {date_num} on its own for sortable plain text, and {time} / {time_secs} for schedule lists and incident channels. Reserved Slack characters inside the URL and fallback (pipe, caret, angle brackets) are escaped automatically so the placeholder remains valid, and the fallback field auto-fills with the live preview if you leave it blank so a missing fallback never silently breaks the message. Useful for Slack bot authors using chat.postMessage and chat.scheduleMessage, incoming webhook senders, on-call rotation tools that announce shift times, release bots, calendar bots, AMA reminders, incident response channels, and any team that schedules cross-zone meetings in Slack. Everything runs locally in your browser; the dates, URLs, and fallback text you type are never uploaded.

Free to use. Works in your browser. No signup, no login.