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Free System Design Tool Online — Draw HLD & LLD Diagrams (2026)

System design interviews, architecture reviews, and infrastructure planning all need clear diagrams. Most tools require signups or paid plans. Here is how to use Toolkiya's free system design tool to create professional architecture diagrams in minutes.

What You Can Build

The tool supports three main diagram types that cover most software engineering needs:

  • High-Level Design (HLD) — Shows the overall system architecture with major components like load balancers, servers, databases, and queues.
  • Low-Level Design (LLD) — Dives into a single service showing controllers, services, repositories, DTOs, and data models.
  • Infrastructure Diagrams — Maps out your cloud setup including CDN, storage, compute, and networking components.

Pre-Built Templates

Instead of starting from a blank canvas, pick from six architecture templates:

  • Monolith — Client, web server, and database in a simple stack.
  • Microservices — API Gateway routing to Auth, Order, and Payment services with dedicated databases.
  • Event-Driven — Producers pushing to a message queue consumed by multiple workers.
  • 3-Tier Web App — Load balancer, app servers, Redis cache, and PostgreSQL.
  • Static Site + CDN — Users hitting a CDN that pulls from an origin with blob storage.
  • REST API (LLD) — Controller to Service to Repository pattern with DTOs and Models.

Infrastructure Cost Estimator

One unique feature is the built-in cost simulator. Add cloud components like servers, databases, load balancers, and caches, then toggle between AWS, GCP, and Azure pricing to see estimated monthly and yearly costs. The breakdown shows spending by category: compute, database, network, and storage.

How to Use It

  1. Open the System Design Tool.
  2. Click Templates to load a starting architecture, or draw freehand.
  3. Edit shapes, add text, draw arrows — full Excalidraw canvas.
  4. Click Cost Estimator to add infra components and see pricing.
  5. Click Export PNG to download your diagram.
  6. Diagrams auto-save to your browser — come back anytime to continue.

Use Cases

  • System design interview preparation
  • Architecture documentation for your team
  • Cloud infrastructure planning and cost estimation
  • Technical proposals and RFCs
  • Onboarding diagrams for new developers

Ready to draw?

No signup, no watermarks, no limits.

Open System Design Tool