CompassPad — Find what was just built.

Railway is an application hosting platform that takes a repository and runs it. The workflow is deliberately short: connect a Git provider, pick a repository, and Railway detects the language, installs dependencies, builds, and starts the process. Databases and other services are added as separate components in the same project. The product's model is a project containing services. A service can be a repository deployment, a database from a template, or a container image. Services reference each other through generated environment variables, so a web service gets a database connection string without a manual copy step. Configuration is optional rather than required. A repository with no build file still deploys through language detection, and a repository that needs control can add a config file to override the build command, the start command, or the health check. The platform publishes usage-based pricing, a status page, and a changelog, which is what makes the operational claims checkable.

Farcaster is a social network protocol with a deliberately unusual property: an account and its messages are not owned by a single application. A user registers an identity, and posts are stored in a way that any client can read, so several applications can serve the same social graph. Messages are signed by the user's key and stored on a peer-to-peer network, with the identity registered on-chain. Because the graph is public and portable, a client is a view rather than the network itself, and a user can move between clients without losing their followers. Frames, an embedded interactive post format, made the protocol useful for applications beyond reading a feed. The model has real friction. Registration costs money, the user experience of managing a wallet and keys is unfamiliar, and the network is much smaller than a mainstream platform. Its appeal is to people who want the social graph to be a public good rather than a company's asset.

Vendure is a headless commerce framework for TypeScript teams. It is built on NestJS with a GraphQL API, and its plugin system is the same module system the framework itself uses, so extending it means writing a NestJS module rather than working around a closed extension point. The commerce domain covers products with variants and facets, carts and checkout, orders, payments, promotions, and multi-channel selling. The admin dashboard is an Angular application that consumes the same API and can be extended with custom UI components. Vendure is a framework rather than a hosted product. A project owns the deployment and the storefront, and upgrades require attention because the plugin API is part of the application. It fits teams already invested in TypeScript and NestJS who want commerce primitives they can shape in code.

Uniswap is a decentralised exchange protocol on Ethereum and other EVM chains. Instead of an order book, trades execute against liquidity pools that anyone can deposit into, with prices determined by a formula rather than by matching a buyer to a seller. The design is what made it influential. A token can be traded as soon as someone creates a pool for it, without a listing process, and the pool's liquidity providers earn a share of the trading fee. The interface is a website, but the exchange itself is a set of contracts, so anyone can build another interface or route trades through it. The tradeoffs are inherent to the model. A large trade moves the price against itself, which is why aggregators split orders across pools. Liquidity providers face loss relative to simply holding the assets when prices diverge, and the user experience requires a wallet, gas, and an understanding of what a failed transaction costs.

PostHog is a product analytics platform that bundles several tools a product team usually buys separately: event analytics, session replay, feature flags, experiments, and surveys. The argument for bundling is that these tools answer related questions and are more useful when they share one event stream. The analytics core is an event pipeline. A product sends events with properties, and the platform builds funnels, retention curves, and paths from them. Session replay records the interface alongside those events, so a drop-off in a funnel can be watched rather than only counted. Feature flags and experiments read from the same user identity, which is what closes the loop: a flag can gate a change, an experiment can measure it, and the funnel shows the result. The platform is published as open source and can be self-hosted, though the self-hosted deployment is a heavier operational commitment than the hosted service.

Coursera is an online learning platform that hosts courses from universities and companies. A course is a sequence of video lectures, readings, and graded assessments, and completion produces a certificate that can be verified through a public URL. The platform's distinguishing feature is the credential. Courses come from named institutions, and several are assembled into specialisations or professional certificates that represent a longer commitment. Graded work is submitted and evaluated, which is what separates the platform from a video library. The tradeoff is the format. A recorded course cannot adapt to a learner the way a tutor or a cohort programme can, and the completion rates for self-paced online courses are low across the category. The platform also sells degrees, which are a different commitment and price point from the individual courses.

Headspace is a meditation and wellbeing application. Content is delivered as guided audio sessions, organised into courses that build a skill over several days rather than as an open library of tracks. The product's strength is production and structure. Sessions are narrated and scored consistently, the beginner course introduces a technique progressively, and themed packs address specific situations such as sleep, focus, or stress. Sleep content includes stories and soundscapes alongside guided sessions. It is a subscription product with a limited free tier. The tradeoff compared with a free meditation library is cost, and the tradeoff compared with a live teacher is that a recorded session cannot adapt to what a person is actually experiencing. It suits someone who wants a structured introduction and consistent production quality.

Clerk is an authentication service that ships prebuilt user interface components alongside the underlying session infrastructure. The pitch is that sign-in, sign-up, profile management, and organization switching should not be a multi-week build for every application. The integration is a set of components rather than a form the developer assembles. A React application mounts a provider, and the sign-in and user-profile surfaces render with the application's styling. Underneath, Clerk manages sessions, password hashing, multi-factor flows, and social providers. Beyond basic authentication, Clerk models organizations: a user can belong to several organizations with different roles, and the session carries the active organization so application code can authorize against it. The service publishes documentation, a changelog, and a status page, and the SDKs are open source even though the service itself is not.

Khan Academy is a non-profit education platform offering a full curriculum from primary mathematics through to advanced subjects, free of charge. Content is organised into courses, each broken into units with instructional videos, articles, and practice exercises. The pedagogical model is built around practice rather than video alone. Exercises are generated with randomised parameters, so a learner can attempt a skill repeatedly, and the system tracks mastery at the skill level. That data drives a dashboard showing which skills are secure and which need work. The platform is free and funded by donations, with no advertising and no paid tier for learners. Its limitation is scope and depth: it covers standard curricula well, but it does not offer the credentialing, the live instruction, or the specialised advanced content that a university programme or a paid platform provides.

Grafana is a visualization and dashboarding platform. It queries data sources - Prometheus, Loki, PostgreSQL, and many others - and renders the results as panels arranged on a dashboard. The product's longevity comes from that separation: Grafana does not store most of the data it displays, it queries systems that do. The query model is per-panel. A panel selects a data source, runs a query, and applies a visualization. Because data sources are pluggable, the same dashboard tool works across a metrics database, a log store, and a SQL database without moving data between them. Alerting is built on the same queries. A rule evaluates a query on a schedule and fires when a condition holds, which means an alert and the dashboard panel that motivated it are defined in the same language. The core is open source and self-hostable, and the hosted service is the commercial layer.

OpenSea is a marketplace for non-fungible tokens. A seller lists an item by signing an order, and the transfer settles on-chain when a buyer accepts, which means the marketplace itself never holds the asset. The product is organised around collections. A collection groups tokens that share a contract and a theme, and its page shows floor price, volume, and listed items. That structure is what makes a large set of individually distinct tokens navigable, and it is why the marketplace became the default place to look up a collection's activity. The tradeoffs are the marketplace's and the asset's. Listing is free because it is only a signature, but settlement costs gas, and a listing can be bypassed if the same asset is sold elsewhere. Fees and royalty enforcement have changed repeatedly, which matters to creators whose income depended on secondary sales.

Ethereum is a public blockchain whose distinguishing feature is that it executes general-purpose programs. A smart contract is code deployed to the network, and any account can call it, which turns the chain from a payments ledger into a platform other applications are built on. The network is maintained by validators who stake ether and are rewarded for proposing and attesting to blocks, with penalties for misbehaviour. Because every node verifies every transaction, the state of the chain is agreed without a central operator. Fees are paid in ether and scale with the computational work a transaction requires. The tradeoffs are the reason alternative chains exist. Throughput is limited by the requirement that every node process every transaction, so fees rise when demand is high. Contracts are immutable once deployed unless written to be upgradeable, which means a bug can be permanent. And the account model puts the burden of key management on the user, where a lost key means lost funds.