Learn · Build · Ship · Grow

You don't become an engineer by watching.

A realistic journey from your first repo to production systems — built on real engineering problems.

Apply now ↗See the path ↓

30+
developers building: 50+
learning episodes: 10+
open-source PRs

A developer working late at a triple-monitor setup overlooking the city

Chapter 01 · Build

Your path

Build
Debug
Ship
Scale
Open Source

A developer working late at a triple-monitor setup

01 / 05Build

You know code. But can you build?

A real repo, a real build, and the error every tutorial skips.

~/task-manager — zsh

$ git clone godevelopers/task-manager

$ npm install

added 312 packages in 9s

$ npm run build

✓ compiled 42 modules

✓ optimized bundle — 184 kB

✗ ERROR DATABASE_URL is not defined

production environment detected.

$

A developer staring at an error highlighted in red on their monitor

02 / 05Debug

It works on your laptop. Why not in production?

Read the graph, trace the error, form a hypothesis — like an on-call engineer.

grafana — p95 latency (ms)

DATABASE CONNECTION TIMEOUT: 2847ms

at pool.acquire (db/pool.ts:41)

at getTasks (api/tasks.ts:18)

→ hypothesis: pool size 5, 400 concurrent requests

A developer at sunset in front of dashboards showing a live product

03 / 05Ship

Your code works. Now ship it.

Pipelines, tests and deploys — until it's live at a real URL.

pipeline #128 — main

feat: realtime task synca1f9c2e

✓Install18s
✓Build42s
✓Test — 128 passed1m 08s
✓Deploy23s

task-manager.godevelopers.spaceLIVE

The glowing path climbing to a flag on the summit

04 / 05Scale

Your app works. Now 10,000 users arrive.

Load balancers, caches and replicas — you design what keeps it standing.

architecture — production

p95

180ms

cache hit

92%

errors

0

A team of developers reviewing a system diagram together

05 / 05Open Source

Don't just use open source. Build it.

Branch, open a PR, get reviewed, get merged — into GoDevelopers' own code.

godevelopers/platform — pull request #214

fix: raise pool size and add query timeout

+48 −12 · 3 files changed

✓ reviewed by 2 maintainers

✓ all checks passed

⇄ Merged into main

Capstone projects

Don't build toy projects. Build systems that survive production.

Each capstone is modelled on a real product's hardest problem. You build it, put it under load, watch it break — then fix it.

Project 01 / 04IntermediateReal-time collaboration

Multiplayer Docs Editor

A Google-Docs-style editor where a whole team types into the same document at the same time.

The hard part

Two people type in the same spot at the same moment — and neither loses a single character, even offline.

< 50 ms
sync latency: 10k
live documents: 0
lost edits

Next.js
Yjs · CRDT
WebSockets
Redis pub/sub
Postgres

system-design-notes.md Synced

PSV

3 people editing

# Rate limiter design

Token bucket per user, refilled every second.

Store buckets in Redis with a TTL so idle users cost nothing.Paras

Edge case: two regions accept the sameSawan request at once.

VVaishalinow

What happens during a Redis failover? Do we fail open or closed?

CRDT ops 1,284sync 38 ms

Project 02 / 04AdvancedFintech

UPI-style Payments Ledger

Wallets, payments and refunds backed by a double-entry ledger — the way real payment companies do it.

The hard part

Networks retry, users double-tap Pay, webhooks arrive twice. Money must never be charged twice or go missing.

0
double charges: p99 < 200 ms
checkout: 100%
reconciled

Node.js
Postgres · serializable
Idempotency keys
Queues
Webhooks

dashboard · payments

Settled today

₹4,82,190

0 double charges

pay_8Kx21₹1,299.00Captured
pay_8Kx20₹849.00Refunded
pay_8Kx1Z₹2,499.00Pending

POST /v1/payments · Idempotency-Key: 7f3a…c21

↳ 200 replayed — duplicate blocked, card not charged twice

DEBIT

wallet −1,299

CREDIT

merchant +1,299

LEDGER

Σ = 0 ✓

Project 03 / 04AdvancedMobility

Real-time Ride Dispatch

Match riders to the nearest driver while thousands of cars stream their location every second.

The hard part

Finding the closest free driver in under a second — while every driver is moving and two riders want the same car.

< 1 s
rider match: 50k
drivers tracked: Live
ETA updates

Go
Redis GEO
WebSockets
PostGIS
Kafka

dispatch · Bengaluru12,480 drivers online

Surge 1.2×

KA

Driver matched · 0.8 km away

KA 05 MJ 2291 · ETA 3 min

420 ms

Project 04 / 04ExpertMedia

Video Streaming Pipeline

Upload a video, transcode it into a bitrate ladder, and stream it adaptively through a CDN.

The hard part

A 2 GB upload on a flaky connection has to resume, transcode in parallel, and start playing in under two seconds.

4
renditions: < 2 s
time to first frame: Resumable
uploads

FFmpeg
S3
BullMQ workers
HLS
CDN

studio · uploads / system-design-ep-12.mp4

Auto · 1080p

12:0431:40

1080p

HLS ✓

720p

HLS ✓

480p

62%

240p

18%