Productivity

SimpleTax is a small calculator for tax arithmetic. Its page describes it as free to download for iPhone, iPad, and Android, and states that it calculates before-tax, tax rate, tax amount, or total, entirely on the device. The site emphasises that the calculation works from whichever number you start with, uses currency-aware rounding, and keeps data local rather than sending it to a server. It is a single-purpose utility rather than a filing or accounting product: the page describes arithmetic, not returns or bookkeeping.

Open WebUI is a chat front end that runs on your own machine or server and connects to local runtimes such as Ollama and to hosted model APIs. It provides the interface a hosted chat product provides, without the conversation leaving your infrastructure. The feature set covers what a team expects from a chat interface: multiple conversations with history, model switching, prompt presets, document upload for retrieval, and web search integration. Multi-user support adds accounts and roles, so a small team can share one deployment with separate conversations and access to different models. It is a front end rather than a model runtime, so it needs something to talk to. The project is open source and self-hostable, and the tradeoff is operational: running it means running a container, a database, and whichever model backend it is pointed at.

Dify is a platform for building applications on language models. The core surface is a visual workflow editor where a pipeline is assembled from nodes: a model call, a retrieval step, a conditional branch, a code node, and an output. The same project can be exposed as a chat application, an API, or an embedded widget. The retrieval layer is built in. Documents are uploaded, chunked, embedded, and indexed, and a knowledge base can be attached to a node so a pipeline answers from your own material. Prompt templates, variables, and model configuration are part of the workflow rather than scattered through application code. The platform is open source and can be self-hosted, which is why some teams adopt it over a hosted orchestration service. The tradeoff is that a visual pipeline is harder to review and version than code, so teams building something complex often move the final implementation into their own codebase once the shape is settled.

Slack is a messaging platform for organisations, organised around channels. A channel is a named conversation that can be public, private, or shared with an external organisation, and membership is a deliberate act rather than an accident of a contact list. The structure is what distinguishes it from a group chat. Threads keep a reply attached to its parent, so a channel is not consumed by a side conversation. Search covers message history and files, and a shared channel lets two organisations work in the same space without exchanging accounts. The platform's second half is the app directory and workflow builder. Incoming webhooks, slash commands, and bots let an external system post into a channel or accept a command from one, which is how alerts and approvals end up where a team already is. The cost is per-seat pricing and the fact that an organisation's conversation history lives in a vendor account.

Cal.com is a scheduling tool in the category that Calendly defined: a bookable link that reads a calendar's availability and writes an event when someone books. It is open source, which is the main difference, and it can be self-hosted so booking data stays on your own infrastructure. The product supports the expected scheduling features: multiple event types, buffers, minimum notice, round-robin distribution across a team, and routing forms that send a booker to the right event based on their answers. It connects to Google, Microsoft, and Apple calendars for availability and to conferencing tools for meeting links. Self-hosting is the reason many teams choose it, and also the main cost. Running the platform means operating a Postgres database, the application, and its background jobs, plus keeping up with releases. Teams that want scheduling to be someone else's operational problem use the hosted plan instead.

Metabase is a business intelligence tool aimed at the people who have questions rather than the people who write SQL. It connects to a database, reads the schema, and presents a point-and-click query builder alongside a native SQL editor for users who want one. The product's distinguishing choice is that it does not require a modelled semantic layer before it is useful. Connect a database and the tables are immediately explorable, with questions saved as reusable cards and assembled into dashboards. Alerts and subscriptions push a saved question to email or Slack on a schedule. Metabase is open source with a paid enterprise edition that adds features such as granular permissions, sandboxing, and audit logging. It is a good fit for a team that needs self-service reporting over an existing database; it is a weaker fit for heavy financial modelling or for organisations that need a governed semantic layer with versioned metric definitions.

Obsidian is a note-taking application whose defining property is that the notes are files on your disk. A vault is a folder; a note is a Markdown file; a link between notes is a wiki-style reference in the text. Nothing requires a server, and the folder can be put in any sync service or version control system. That choice has consequences. The application works offline because there is nothing to fetch, the notes remain readable if the application is uninstalled, and a user can edit them in any text editor. It also means the user owns the sync and backup decision rather than inheriting one. On top of the files, Obsidian adds a graph view of links, a canvas for arranging notes spatially, and a plugin system. Plugins are community-authored and can add views, commands, and editor behavior, which is how the application covers workflows it does not ship itself.

Craft is a document editor built for Apple platforms first, with a native application rather than a web app wrapped in a shell. Documents are composed from blocks, and the editor supports the formatting and media handling expected of a modern writing tool: tables, code blocks, callouts, and embedded content. The product adds structure on top of the document. Blocks can be linked and referenced, documents can be nested into a hierarchy, and a daily-notes surface provides a place to capture without deciding where something belongs first. Sharing produces a web page with a readable layout rather than a raw export. Craft is a good fit for people who write long-form documents and want a native editor with a strong visual result. It is a weaker fit for teams that need a shared wiki with granular permissions, or for anyone who wants their notes stored as plain files rather than in the application's own format.

Raindrop.io is a bookmark manager that stores more than a URL. When a page is saved, the service captures its content and produces a permanent readable copy, so a bookmark survives the original page changing or disappearing. Organisation is by collections and tags. A collection can be nested and shared, and a saved item can carry tags, a highlight, and an annotation. A full-text search runs over the captured content rather than only the title, which is what makes a large archive useful rather than a list of links. The product has free and paid tiers, with the paid tier adding full-text search across the archive, permanent copies, and larger uploads. It works across browsers and mobile, and imports from other bookmark services. The limitation is that it is a personal archive tool rather than a collaborative knowledge base: shared collections exist, but the product is not built for team editing.

Plane is a project management tool in the issue-tracker category, positioned as an open-source alternative that can be self-hosted. It covers the familiar surfaces: issues, cycles, modules, and views, with a project structure on top. The differentiator is deployment. The product ships as a hosted service and as a self-hostable deployment, and the source is published. Teams that need their project data on their own infrastructure can run it, at the cost of operating it. Plane's model adds modules alongside cycles. A cycle is a timebox; a module is a grouping of issues by theme that can span cycles. Views are saved filters that can be shared across a project, which is how a team keeps a consistent board without rebuilding it per person.

Anki is a flashcard application built on spaced repetition. A card has a front and a back, and after each review the learner rates how difficult the recall was. That rating determines when the card is shown again, so material that is easy is seen rarely and material that is hard is seen often. The scheduling algorithm is the product. Decks are user-created, and the shared deck library means a learner can start from someone else's deck for a standard subject. Because the algorithm is open and the file format is documented, decks can be generated programmatically from other data. The interface is functional rather than polished, and creating good cards is work: a poorly written card produces poor recall no matter how good the schedule is. The application is free on desktop and Android, with a paid iOS client that funds development, and synchronisation runs through a free account.

Twenty is a customer relationship management tool built as an open-source alternative to established CRM platforms. Its distinguishing design decision is that the data model is editable: a team defines its own objects, fields, and relationships rather than adapting to a fixed schema. A CRM's value comes from the shape of its records, and most platforms fix that shape. Twenty exposes it. Companies, people, and opportunities are the defaults, but a team can add objects, add fields to existing objects, and define relations between them. Views and filters are built on top of whatever model the team creates. The product is published as open source and can be self-hosted. The hosted service is the commercial layer. For teams whose CRM requirements do not match a standard sales pipeline, the editable model is the reason to consider it.

Raycast is a macOS launcher: a keyboard shortcut opens a search field that reaches applications, files, clipboard history, and window management. The launcher is the surface; the extension API is what makes it a platform. An extension is a small program that adds commands to the launcher. A command can render a list, a form, or a detail view, and it can call an API. Because the UI primitives are provided, an extension that talks to a service is a few hundred lines rather than a full application. The store distributes extensions, and installing one adds its commands to the same search field as everything else. That consolidation is the practical argument: instead of remembering which app owns which action, a user reaches all of them through one shortcut. The product is proprietary and macOS-only, which is the main constraint to weigh.

Mintlify is a documentation platform for product and API docs. The workflow is content-first: a team writes Markdown and an OpenAPI specification in a repository, and the platform builds a documentation site with navigation, search, and an API reference generated from the specification. The generated API reference is the part that saves the most work. Instead of hand-writing a page per endpoint, a team points the platform at an OpenAPI document and the reference pages are produced from it, with request and response examples and a try-it panel. Because the source of truth is files in a repository, documentation changes go through the same review as code. The platform renders the result, hosts it, and provides the search and navigation layer. Content is written in MDX, so a page can include components beyond plain Markdown when a diagram or a tabbed example is needed.

n8n is a workflow automation tool that connects services through a visual node editor. A workflow is a graph: a trigger node starts it, and subsequent nodes call APIs, transform data, or branch on conditions. The product sits between two categories. It is more visual than writing an integration script, and more code-friendly than a consumer automation tool: nodes can include JavaScript expressions, and a code node can run arbitrary logic inside the workflow. That combination is what lets it handle a transformation that a purely visual builder cannot express. n8n is published as source and can be self-hosted, which matters for teams that need automation to run inside their own network. The hosted cloud is the commercial layer. The self-hosted deployment is the same core, so a workflow can move between them.

Excalidraw is a virtual whiteboard that renders shapes with a hand-drawn line style. The aesthetic is deliberate: a diagram that looks sketched reads as a work in progress, which changes how a team treats it during a discussion. The product runs in the browser with no account required for a basic session. A drawing can be exported as an image or a file, shared through a link, and embedded in another page. For teams that need persistence and collaboration, an end-to-end encrypted room or a self-hosted deployment is available. The source is published and the project is widely embedded: several documentation tools and editors use Excalidraw's component rather than building their own diagram surface. That reuse is the clearest evidence that the drawing layer is separable from the hosted app.