What is LiteJoin?

Turn any API into a real-time stream. Join data with SQL. Deploy as a single binary.

What is LiteJoin?

LiteJoin is a real-time streaming engine that lets developers turn any REST API into a live event stream, join data across sources with standard SQL, and deploy the entire pipeline as a single binary. No Kafka. No JVM. No cluster to manage.

API → Stream

Point LiteJoin at any REST API. It polls, diffs, and emits only the changes — turning request/response into real-time events automatically.

SQL Joins

Write familiar SELECT ... JOIN queries to combine data from multiple streams. LiteJoin evaluates joins in real-time as new data arrives.

Single Binary

The entire engine — storage, joins, windows, sinks — ships as one Go binary backed by SQLite. No external dependencies.

LiteJoin Studio

A visual desktop app for building pipelines. Add sources, write SQL, see live results, and export a production-ready config file.

Why LiteJoin?

Stream processing has historically required heavy infrastructure: Kafka for messaging, Flink or ksqlDB for processing, and a team to keep it running. Most developers just need to:

1. Watch an API for changes — “Tell me when a Stripe charge status changes”
2. Enrich with context — “Join that charge with customer data from another API”
3. React in real-time — “Send the enriched result to a webhook or dashboard”

LiteJoin does all three with a YAML config file and a single command:

litejoin run -c litejoin.yaml

How It Works

# litejoin.yaml — a complete pipeline
sources:
  - name: stripe_charges
    type: api
    topic: charges
    api:
      url: "https://api.stripe.com/v1/charges?limit=100"
      interval: 10s
      key_path: "id"
      response_path: "data"
      headers:
        Authorization: "Bearer ${STRIPE_SECRET_KEY}"

  - name: stripe_customers
    type: api
    topic: customers
    api:
      url: "https://api.stripe.com/v1/customers?limit=100"
      interval: 5m
      key_path: "id"
      response_path: "data"
      headers:
        Authorization: "Bearer ${STRIPE_SECRET_KEY}"

joins:
  - name: charge-customer-join
    query: |
      SELECT
        c.key as charge_id,
        c.payload as charge,
        cust.payload as customer
      FROM charges c
      LEFT JOIN customers cust
        ON json_extract(c.payload, '$.customer') = cust.key
      WHERE c.timestamp > (strftime('%s', 'now') - 60)
    sink: webhook_out

sinks:
  - type: http
    name: webhook_out
    config:
      url: "http://localhost:9000/webhook"

LiteJoin polls both APIs, detects changes (new charges, updated customers), joins them in real-time using SQL, and forwards enriched results to your webhook.

Use Cases

Scenario	How LiteJoin Helps
Payment enrichment	Poll Stripe charges + customers → joined stream with full context
DevOps dashboards	Poll GitHub PRs + Jira tickets → velocity metrics joined on branch name
Price monitoring	Poll competitor pricing APIs → detect and alert on changes
IoT correlation	Ingest sensor data via HTTP → window + aggregate in real-time
Audit trails	Capture every API state change with field-level diff metadata

Next Steps

Quickstart

Install LiteJoin and run your first pipeline in 5 minutes.

Core Concepts

Understand sources, streams, joins, windows, and sinks.