Offline Push

The video uses a specific AI coding tool to demonstrate the setup, but the configuration works 1:1 with Cursor, Claude Code, or any other tool. Despia is web framework and tooling agnostic, so the only thing that matters is the SDK call with the scheme parameters.

sendlocalpushmsg:// schedules a local notification on the device after a delay you specify in seconds. The OS surfaces the notification even if your app is closed, and tapping it opens the URL you passed in. Everything happens client-side, no server, no network call, no OneSignal account required.

This feature is fully supported and a good fit for short-lived, contextual reminders that the user just set themselves (a 10-minute timer, a “remember to drink water in 2 hours” tap). For anything else, especially anything where your backend is the source of truth (scheduled marketing, transactional alerts, time-zone-aware drip sequences), use OneSignal instead. OneSignal’s send_after and delayed_option: timezone parameters cover the same scheduling space with the durability and observability of server-sent push.

Installation

Bundle
CDN

npm install despia-native

pnpm add despia-native

yarn add despia-native

import despia from 'despia-native';

<script src="https://cdn.jsdelivr.net/npm/despia-native/index.min.js"></script>

<script type="module">
    import despia from 'https://cdn.jsdelivr.net/npm/despia-native/+esm'
</script>

How it works

The scheme packs four values into a single URL: delay in seconds, message body, title, and deep-link URL. The runtime registers the notification with the OS scheduler and returns immediately. There is no return value and no callback when the notification fires.

import despia from 'despia-native'

const isDespia = navigator.userAgent.toLowerCase().includes('despia')

if (isDespia) {
    despia('sendlocalpushmsg://push.send?s=5=msg!Don't forget to save&!#Quick reminder&!#https://myapp.com/save')
}

The format is fixed: s= followed by the delay, =msg! followed by the body, &!# followed by the title, &!# followed by the deep-link URL. The unusual delimiters exist so the scheme parser can tell the four fields apart even when their values contain spaces or punctuation.

Scheme parameters

Parameter	Position in URL	What it carries
Delay	`s={n}`	Seconds until the notification fires. Use `0` for immediate, larger values for scheduled
Message	`=msg!{body}`	The notification body text the user reads
Title	`&!#{title}`	The notification title shown above the body
Deep link	`&!#{url}`	The URL to open in the WebView when the user taps the notification

Encode any user-supplied values with encodeURIComponent to avoid breaking the parser when the message or title contains &, #, !, or =.

function scheduleReminder(seconds, title, body, url) {
    if (!isDespia) return

    const t = encodeURIComponent(title)
    const b = encodeURIComponent(body)
    const u = encodeURIComponent(url)

    despia(`sendlocalpushmsg://push.send?s=${seconds}=msg!${b}&!#${t}&!#${u}`)
}

scheduleReminder(60, 'Stretch break', 'Time to stand up', 'https://myapp.com/wellness')

Schedule a self-set reminder

The natural fit for offline push is a reminder the user just set themselves. The interaction is one-shot, the delay is short, and the user already knows what’s coming, so a server is unnecessary.

import { useState } from 'react'
import despia from 'despia-native'

const isDespia = navigator.userAgent.toLowerCase().includes('despia')

function TimerButton() {
    const [minutes, setMinutes] = useState(10)

    function startTimer() {
        if (!isDespia) return

        const seconds = minutes * 60
        const body    = encodeURIComponent(`Your ${minutes}-minute timer is up`)
        const title   = encodeURIComponent('Timer')
        const url     = encodeURIComponent('https://myapp.com/timer')

        despia(`sendlocalpushmsg://push.send?s=${seconds}=msg!${body}&!#${title}&!#${url}`)
    }

    return (
        <div>
            <input
                type="number"
                value={minutes}
                onChange={e => setMinutes(Number(e.target.value))}
            />
            <button onClick={startTimer}>Start {minutes}-minute timer</button>
        </div>
    )
}

When to reach for OneSignal instead

Offline push is the right tool when the user just set the reminder, the delay is short, and missing the notification would not break anything. Reach for OneSignal when any of the following apply:

Need	Why offline push falls short	What OneSignal gives you
Schedule from your backend	Offline push only fires from a JavaScript call inside the app	`send_after` parameter on the REST API, scheduled server-side
Deliver at a specific local time across time zones	Seconds-based delays drift relative to the user’s clock	`delayed_option: 'timezone'` plus `delivery_time_of_day`
Send to users who do not have the app open	The app has to run for the schedule to register	Cloud-delivered, no app launch required
Cancel or update a notification after scheduling	No cancel API, the notification fires regardless of app state changes	Notification IDs returned by the REST API for later cancellation
Audit which users received which notifications	Fully client-side, no record exists outside the device	Full delivery analytics in the OneSignal dashboard
Target by tag, segment, or behavior	Each call is per-device with no targeting layer	`filters` and `included_segments` for behavioral targeting

For anything where your backend should be the source of truth, OneSignal is worth the integration cost. Offline push is best kept to user-initiated, in-the-moment reminders.

Resources

NPM Package

despia-native

Support

support@despia.com

Deployment

Best Practices

Local Ecosystem

Authentication

Payments

Analytics

Connectivity

Machine Learning

Wallets

Native Features

Roadblocks

Store Rejections

Platform Support

Installation

How it works

Scheme parameters

Schedule a self-set reminder

When to reach for OneSignal instead

Resources

NPM Package

Support

​Installation

​How it works

​Scheme parameters

​Schedule a self-set reminder

​When to reach for OneSignal instead

​Resources

NPM Package

Support

Installation

How it works

Scheme parameters

Schedule a self-set reminder

When to reach for OneSignal instead

Resources