4th Cross Labs

We are an open source hacker collective named after 4th Cross street, JP Nagar (Bengaluru) where at Zerodha, we started hacking more than a decade ago.


Featured projects (18)

Full-featured, self-hosted applications ready to run out of the box. The Zerodha icon icon indicates projects in use in production at Zerodha.

listmonk screenshot
High performance, self-hosted, newsletter and mailing list manager with a modern dashboard. Single binary app.
libredesk screenshot
Open-source, self-hosted customer support desk in a single binary. A lightweight alternative to Intercom, Zendesk, Chatwoot.
logchef screenshot
Lightweight, single-binary log analytics interface for ClickHouse, focused on high-performance querying and visualization
dungbeetle
A distributed job server built specifically for queuing and executing heavy SQL read jobs asynchronously. Separate out reporting layer from apps. MySQL, Postgres, ClickHouse.
Standalone server for user address and OTP verification flows with pluggable providers (e-mail, SMS, bank penny drops etc.)
Replicate and sync Kafka topics between clusters in realtime. Supports topic re-mapping, healthchecks, and hot failovers for high availability.
oore.build screenshot
Self-hosted, Flutter-first mobile CI and internal app distribution platform.
torii screenshot
Identity-aware reverse proxy with built-in auth, session management, RBAC and an embedded admin UI. Single binary app.
dictpress screenshot
A stand-alone web server application for building and publishing full fledged dictionary websites and APIs for any language.


More projects (115)

Check out individual maintainer websites for even more projects.

Ultra-lightweight, zero dependency, semantic HTML, CSS, JS UI library. ~10KB min+gz.
koanf
Simple, extremely lightweight, extensible, configuration management library for Go. Supports JSON, TOML, YAML, env, command line, file, S3 etc. Alternative to viper.
A DNS server that offers useful utilities and services over the DNS protocol. Weather, world time, unit conversion etc.
Simple command-line utility to convert CSV, TSV and Excel files into a single self-contained HTML page with search, filters, and sorting
A super tiny Javascript library to make DOM elements draggable and movable. ~500 bytes (minified+gzipped) and no dependencies.
A super tiny Javascript autocomplete / autosuggestions library. Zero dependencies, ~800 bytes min+gzip.
Compress and embed static files and assets into Go binaries and access them with a virtual file system in production
High throughput Go SMTP pool library with graceful handling of idle timeouts, errors, and retries.
A tiny Go library + client for downloading Youtube videos. The library is capable of fetching Youtube video metadata, in addition to downloading videos.
linkpage
LinkPage is a FOSS self-hosted alternative to link listing websites such as LinkTree and Campsite.bio
A tiny Javsacript library for sideloading static assets on pages and caching them in the browser's IndexedDB for longer-term storage.
A simple Go POP3 client library for connecting and reading mails from POP3 servers.
A CLI utility and web server for digitally signing PDFs with docsign loaded from PFX (PKCS#12) files
Fastglue is an opinionated, bare bones wrapper that glues together fasthttp and fasthttprouter to act as a micro HTTP framework.
apkc is a bare-bones Android app build system that lets you build simple native Android apps without entire Android IDE
simplesessions is a Go session management library that is completely agnostic of HTTP libraries and frameworks, backend stores, and even cookie jars.
Parse SQL files with multiple named queries and automatically prepare and scan them into structs.
dirmaker is a simple, opinionated static site generator for quickly publishing directory websites.
A utility for downloading, parsing and sanitizing bank database (IFSC, MICR, address etc.) Excel sheets from the RBI website.
KNphone is a phonetic algorithm for indexing Kannada words by their pronunciation, like Metaphone for English.
A tiny (~750 bytes, min+gzip) Javascript library for rendering tabbed UIs. Zero dependencies.
csv2json is a fast utility that converts CSV files into JSON line files. An experiment in Zig lang.
Live preview and render Go templates with custom data, in the browser or on the command line.
A simple wrapper over Go runtime/pprof for running multiple concurrent profiles and dumping results to files.
fastcache is an HTTP response caching package that plugs into fastglue that simplifies "dumb" caching of API endpoints.
A frappe app that has workflows and reports to make payments to vendors by a company and track them
Parse SQL files with multiple named queries into a map for easy organisation and management of SQL queries. Port of goyesql.
git tag bump: A simple utility to bump and manage git semantic version tags and generate Markdown changelogs.
Tiny i18n library for loading and using simple JSON language translation files in Go programs.
tagflow
Native rich content runtime for flutter apps, with html rendering, trusted json documents, and live content patches
Commandline utility to convert config formats like TOML, JSON, YAML etc to KV Pairs which can be imported via consul cli.
Vagrant based setup for local Nomad/Consul clusters. Helpful for experimenting with Nomad job specs in an environment similar to production.
chunkedreader is a light weight wrapper for Go's `bufio` that enables reading of byte streams in fixed size chunks
A utility to archive all closed tickets beyond a certain age to disk (including attachments) and delete them from the database. The tickets are archived as JSON files.
Collaborative group food ordering on Swiggy. Participants submit items to a shared session and the organiser syncs the combined cart.
Go-native, npm-compatible package manager and esbuild bundler in a single static binary. No node, npm or bun.
A Postgres extension that relays SQL table function calls to an external daemon over HTTP and returns its rows.