Real-time alerts from your own infrastructure to your phone, with no Firebase, Pushover, or third-party push service in the path: Gotify is a simple, self-hosted notification server written in Go. The model is deliberately minimal: senders push messages with a single HTTP POST to the REST API, receivers subscribe over a WebSocket stream, and a clean React web UI manages the pieces. Senders are namespaced as "applications," each with its own token, so your backup script, Uptime Kuma, CI pipeline, and cron jobs each get an identity, an icon, and independently revocable credentials - centralized alerting from many services with per-source management. Messages carry a title, body, and priority level that maps to notification importance on the client. The official Android app (on both F-Droid and Google Play, notable for working entirely without Google Play Services) shows push notifications for new messages; the web UI itself supports Web Push in the browser; and gotify/cli pushes messages from shell scripts with one command. A server-side plugin system adds custom behavior, and the whole thing runs as a single small binary with SQLite by default - near-zero resource footprint. Because dozens of tools (and Apprise) speak Gotify natively, it slots in as the notification hub for an entire homelab or ops stack.

Automate transactional and marketing messages across email, SMS, mobile push, WhatsApp, Slack, and custom webhooks from a single visual journey canvas. Dittofeed provides the capabilities of Customer.io or Braze while keeping customer PII within your own infrastructure and eliminating volume-based pricing entirely. The drag-and-drop journey builder creates multi-trigger automations with branching logic, wait nodes, random cohort splits for A/B testing, and local timezone delivery without writing code. User segments combine trait conditions, event history, and array-based filtering through AND/OR operators with real-time evaluation. Template authoring supports both a low-code visual editor and direct HTML/MJML input, with templates reusable across journeys and one-off broadcasts. Data flows in through Segment integration, Reverse ETL connections, or the REST API with Web, Node.js, and React Native SDKs. Message delivery routes through SendGrid, Amazon SES, Twilio, or SignalWire with per-channel analytics tracking opens, clicks, bounces, and unsubscribes. Authentication supports Keycloak, AWS Cognito, and GCP OAuth for enterprise SSO. Embeddable iframe and headless React components let SaaS platforms white-label journey builders into their own products. Deploy on RepoCloud with a dedicated VPS for full GDPR compliance under the MIT license.

Your monitoring should be able to tap you on the wrist, not just write to a log nobody reads. Bark is an open-source push notification server for iPhone and iPad: any script, cron job, or monitoring tool sends one HTTP request to your server, and a custom notification lands on your iOS device through Apple's push service, usually within a second and without draining the battery. Notifications carry titles, subtitles, bodies, badges, custom icons, and sounds, and the iOS-only vocabulary is fully supported: grouping related alerts together, time-sensitive delivery that breaks through Focus, critical alerts that keep ringing for thirty seconds, and tap actions that open a URL or copy a value to the clipboard. Batch keys notify several devices at once, archived messages can carry a time-to-live before they delete themselves, and encrypted pushes keep content unreadable to anyone in the middle. The server itself is deliberately tiny: one container or binary listening on a port, device tokens stored in a local file database by default, an endpoint to register devices, health checks for your supervisor, and even an MCP interface so AI agents can notify you through the same pipe. Cron jobs, backup scripts, CI pipelines, and home automations all gain a voice that reaches the phone in your pocket. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Families and small communities run their own messenger with Databag, where accounts live on a little home server and chats never pass through a platform company. Conversations live in topics instead of contact threads, so the ski trip, the shopping list, and the school parents each keep their own stream with unlimited participants. Seal a topic and end-to-end encryption means even you, the admin, cannot read it on the server. Friends on other Databag nodes join the same topics because accounts federate across servers, and identity comes from a public-private key pair rather than a phone number or a rented domain. Photos, videos, and files ride along in the thread, audio and video calls connect from the mobile and browser apps, and push alerts arrive through UnifiedPush, FCM, or APN when something new lands. The whole node sips resources, happily running on a Raspberry Pi class machine, and websockets deliver messages with low latency instead of polling. Host unlimited accounts for the whole household, protect sign-in with TOTP multi-factor authentication, and manage everything from apps on iOS, Android, F-Droid, or any browser. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

NitroPing sends push notifications to your iOS, Android, and web apps through Apple APNs, Firebase FCM, and Web Push, from a service you host yourself instead of a rented vendor. Create an app to receive its API key, register each device token with its platform, then send notifications to chosen devices with a GraphQL mutation. Provider credentials for APNs, FCM, and Web Push are stored encrypted per app, so several projects can share one instance with isolated keys and data. Delivery tracking records every send with its status, and analytics views show performance metrics and real-time updates as notifications land. Apps are managed with JWT sign-in and per-app API keys, rate limits protect the endpoints, and webhook secrets sign delivery callbacks to your servers. Native Swift and Kotlin SDKs handle registration inside iOS and Android apps, so the device side needs a few lines instead of a custom client. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Powering notification delivery for thousands of organizations with over 39,000 GitHub stars, Novu is the open-source communication infrastructure that eliminates the need to build separate integrations for every messaging channel. The TypeScript-based platform provides a single API endpoint that routes notifications across In-App Inbox, Email via SendGrid, Mailgun, AWS SES, and Postmark, SMS through Twilio, Vonage, and Plivo, Push via Firebase Cloud Messaging, Expo, and APNS, and Chat through Slack, Discord, Microsoft Teams, and WhatsApp. The embeddable React Inbox component delivers real-time WebSocket-powered notifications with read/unread states, action buttons, and user-controlled preferences directly inside your application. The workflow engine orchestrates complex multi-channel delivery with conditional branching, time delays, digest batching to reduce notification fatigue, throttle controls, and per-step channel fallbacks. Novu Connect introduces Agent Communication Infrastructure enabling AI agents built with LangChain, Claude, or custom frameworks to hold threaded two-way conversations with humans across any supported channel through a single conversation model with identity resolution and credential management. The backend runs on Node.js with NestJS, MongoDB for notification storage, Redis with BullMQ for job queuing, and Socket.io for real-time delivery. Self-hosting deploys via Docker Compose with the dashboard accessible at port 4200. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

One REST call, 130+ notification services: Apprise API wraps the well-known Apprise library in a lightweight Django/Gunicorn microservice, so "send an alert" works the same whether it goes to Slack, Discord, Telegram, Teams, email, SMS, Pushover, or PagerDuty - each addressed by a simple URL scheme. It solves the credential-sprawl problem cleanly: instead of embedding provider tokens in every app, cron job, and CI pipeline, you centralize them here and everything else just POSTs a body and title. Two modes cover every workflow. Stateless calls to /notify carry target URLs in the payload (or fall back to a default set via APPRISE_STATELESS_URLS); stateful mode stores named configurations server-side under keys, so /notify/{KEY} fans out to everything registered - with tag-based routing (comma for OR, space for AND) selecting which endpoints fire per message. Messages take info, success, warning, or failure types in text, Markdown, or HTML, with attachments up to a configurable size. A built-in web UI manages and tests configurations, APPRISE_CONFIG_LOCK makes the store read-only, service allow/deny lists restrict which schemes work, webhook remapping adapts third-party payloads, and a Prometheus /metrics endpoint watches the gateway itself.

A flight recorder for production code, Parca profiles CPU and memory continuously and keeps the history to query after something breaks. A slow memory leak or a momentary CPU spike is already on record by the time anyone looks. Point it at any service that exposes pprof endpoints, or deploy the eBPF-based Parca Agent to profile every process on a Linux host or Kubernetes node without touching application code. The agent covers C, C++, Rust, Go, and more. In the web UI, pick a profile type such as on-CPU, narrow it with Prometheus-style label selectors, sum or group by any label, and click a point on the time series to open its flame graph. Switch the same query to a table, add extra panels, or try the alpha Flame Chart and Sandwich views. After a deploy, open the Compare page, set two queries side by side by label or time range, and the functions that gained or lost CPU time stand out as a diff. Native binaries are symbolized from uploaded debuginfo or upstream debuginfod servers. Recent releases add support for OpenTelemetry eBPF profiler profiles and GPU profile types. Optional persistence keeps history across restarts, and a Prometheus-style scrape configuration with service discovery decides what gets profiled. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

One notify() call is all your product needs to reach users on push, email, SMS, chat, and webhooks, with NotifKit deciding how and when each message travels. List the channels in the order you prefer and NotifKit tries each in turn, so a failed push quietly becomes an SMS or an email instead of a lost message. Per-user preferences, consent, and quiet hours in each user's own timezone hold non-urgent sends until morning, while critical messages such as one-time passwords travel their own lane immediately. Templates, multi-step workflows that wait days or block on events, scheduling, throttling, and deduplication all run behind that single call, defined in TypeScript and kept in your repository. Delivery logs record every attempt, and the admin dashboard shows a live activity feed, queue depth per priority lane, workflow runs step by step, and a replayable dead-letter queue. Several products can share one deployment as separate projects with their own API keys, rate limits, and data, and any service can call the REST API without the TypeScript SDK. Ask an AI assistant why a password reset never arrived by connecting the built-in MCP server to Claude Code, Cursor, or another MCP client. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Mixpanel, OneSignal, and Crashlytics in one self-hosted stack - Countly is an all-in-one product analytics and engagement platform where every byte of first-party data stays on your server. A Node.js application over MongoDB, it collects through ten battle-tested SDKs spanning iOS, Android, web JavaScript, React Native, Flutter, Unity, and desktop (plus a data write API for anything else), and has powered tens of thousands of mobile, web, and desktop apps since 2012. The analytics core covers sessions, custom events, views, user profiles, and real-time dashboards, with exploration tools built for product managers as much as analysts. What separates Countly from pure analytics tools is acting on the data without third parties: built-in push notifications send automated, transactional, and personalized messages to iOS (APNs), Android (Firebase), and Huawei devices, with the SDK handling token retrieval and permission flows automatically; crash reporting captures symbolicated native crashes on iOS and Android plus JavaScript errors, correlated with the same user and session data. Email reports keep stakeholders updated, and the plugin-based architecture means features load as modules. For GDPR-sensitive products, engagement without piping user data to advertising companies is the entire point. AGPL-licensed server, installable in minutes.