LangGraph

LangGraph

Stateful multi-agent graphs

2 case studies
3 specialists
Agents Dev Framework

What it's used for

LangGraph is used to build stateful, multi-step agent workflows as directed graphs where each node is an LLM call, tool invocation, or decision point. It handles complex control flow like loops, branching, and human-in-the-loop patterns that simple chains cannot express.

Getting started

Install with `pip install langgraph` alongside your existing LangChain installation. Define your graph nodes as functions and edges as transitions, then compile the graph into a runnable. LangGraph uses the same LLM provider keys you already have configured for LangChain.

$ pip install langgraph` alongside your existing LangChain installation

Case studies

Real LangGraph projects

8% → 0.4% error rate Financial Services

15-Step Loan Processing Workflow — $50M/Month

Regional bank, consumer lending division

Challenge

A bank's loan processing workflow required 15 sequential and parallel steps across 4 systems. Manual processing errors were causing 8% of applications to require rework, delaying approvals by 3–5 days.

Solution

Designed a LangGraph state machine mapping all 15 processing steps as nodes with conditional branching, parallel fan-out, and human-in-the-loop checkpoints for edge cases. State persistence enables recovery from any failure point.

Results

Error rate dropped from 8% to 0.4%. Average approval time reduced from 5 days to 18 hours. The system now processes $50M/month in loan volume with 99.7% uptime.

41% → 94% test coverage Developer Tools

Autonomous Test Writer — 41% → 94% Coverage

Series B developer tools startup

Challenge

A 200k-line codebase had 41% test coverage and a backlog of 800 untested functions. Engineering velocity was slowing as bugs introduced in production.

Solution

Built a LangGraph multi-agent system: an Analyzer agent reads code and infers intent, a Test Writer agent drafts tests, a Runner agent executes and reports failures, and a Fixer agent iterates until green. Runs nightly on CI.

Results

Test coverage grew from 41% to 94% autonomously in 6 weeks. Zero critical production bugs in the following 6 months. Engineers saved an estimated 400 hours of test-writing time.

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