Web3 Infrastructure: RPCs, Nodes, Infura/Alchemy (The Invisible Plumbing)

Source: Dev.to

Blockchains Are “Blind” Without Nodes

Remember Day 6?
Smart contracts live on‑chain, but they can’t “see” your wallet balance, pending transactions, or the current block without asking someone.

That “someone” is an RPC node – a computer constantly synced to the blockchain, ready to answer questions like:

• “What’s my ETH balance?”
• “Did my transaction confirm?”
• “What’s the latest block?”

Without nodes, MetaMask is just a fancy calculator with no internet connection.

Analogy: Your phone doesn’t store the entire internet; it asks Google (“Hey, what’s the weather?”). RPC nodes are Web3’s Google.

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What Is an RPC Node? (Simple Version)

• RPC = Remote Procedure Call – computer A asks computer B to run a function and return the result.
• RPC Node = a full copy of the blockchain that:
  • Downloads every block, transaction, and smart‑contract state.
  • Speaks JSON‑RPC (the standard language for blockchain queries).
  • Acts as a middle‑man between your dApp/wallet and the chain.

Every time you:

• Check a balance in MetaMask
• Send a transaction
• Query Uniswap prices

MetaMask sends an RPC request to a node somewhere.

Real example: When you deployed your first contract on Sepolia (Day 9), Remix IDE called an RPC endpoint: “Hey, broadcast this transaction for me.”

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The RPC URL – Web3’s “Phone Number”

Every blockchain connection starts with an RPC URL, e.g.:

https://eth-sepolia.g.alchemy.com/v2/YOUR_API_KEY
https://mainnet.infura.io/v3/YOUR_PROJECT_ID

Breakdown

MetaMask → Settings → Networks → Ethereum Mainnet → RPC URL is exactly this string.

Pro tip: Copy the URL from your Alchemy/Infura dashboard, paste it into MetaMask’s custom network, and you’re instantly connected to any chain.

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Running Your Own Node vs. Using a Provider

Option 1 – Run Your Own (Hardcore)

geth --sepolia --http --http.api eth,net,web3

• Downloads hundreds of GBs.
• Must run 24/7.
• Gives you full control, but incurs electricity costs and crashes when your laptop sleeps.

Best for: Privacy‑focused users, MEV bots, enterprise dApps.

Option 2 – Use a Provider (99 % of devs)

Infura (ConsenSys) and Alchemy power ~90 % of Web3.

When you followed Day 9 Sepolia deploy you already used their node without realizing it.

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Infura vs. Alchemy – Provider Showdown

My pick: Alchemy – better free tier + dashboard makes debugging way easier.

Switching test: Grab free API keys from both, deploy the same contract, and you’ll see comparable speed for small projects.

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Real‑World: How MetaMask + RPCs Actually Work

1. You click “Swap ETH → USDC” on Uniswap.
2. Uniswap asks RPC: “What’s my ETH balance? USDC price?”
3. MetaMask asks RPC: “Can I sign this tx? What’s the gas price?”
4. You approve → MetaMask broadcasts the tx via RPC.
5. RPC broadcasts to Ethereum miners/validators.
6. After ~6 blocks, RPC confirms “Tx success!”

Every step is an RPC call. No RPC = no Web3.

What if Infura goes down? Switch the RPC URL in MetaMask settings – it takes ~30 seconds.

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Why This Matters for Builders (The DevRel Angle)

From my Sepolia deploys: I spent 2 hrs debugging “transaction underpriced” before realizing my RPC was rate‑limited. Never again.

Pro move: Keep 2–3 RPC URLs ready – primary, backup, and (if possible) self‑hosted.

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Hands‑On: Set Up Your Own RPC Pipeline (≈ 5 min)

1. Sign up at a provider (free tier).

2. Create an app → copy the Sepolia RPC URL.

3. MetaMask → Settings → Networks → Add Network

4. Test: Send 0.001 Sepolia ETH to your address. It should appear instantly.

5. Challenge: Deploy the contract from Day 9 using your Alchemy RPC vs. Infura. Compare speed.

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Reflection – The “Aha” Moment

RPCs felt boring until I realized: MetaMask isn’t magic; it’s just a fancy RPC client.

Understanding nodes explains why:

• Transactions get “stuck” (RPC rate limits).
• dApps crash during congestion (provider overload).
• “Private” wallets aren’t truly private (shared RPCs see everything).

Next time someone says “Web3 is just JSON over HTTPS,” nod knowingly.

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Key Takeaway

RPC nodes are Web3’s Google – every wallet click, swap, and contract call goes through them.
Infura and Alchemy handle the bulk of traffic, but knowing how to choose, configure, and (if needed) run your own node is essential for reliable, scalable, and private blockchain development.

# 90% of traffic so you don't have to.

## What to do next

### Learning
- Set up an Alchemy account + add a custom RPC in MetaMask.  
- Read **Day 23 (On‑chain identity)** – remember that ENS queries also hit RPCs (Stay tuned).

### Building
- Bookmark three RPC providers: **Alchemy**, **Infura**, **QuickNode**.  
- Never hard‑code a single RPC URL in production.

### Join us
- Drop your “RPC horror story” below 👇  

[Web3ForHumans](https://t.me/Web3ForHumans) – Telegram: share your node setups!  

Follow me on:  
- [Medium](https://medium.com/@Ribhavmodi)  
- [Twitter](https://x.com/RibsModi)  
- [Future](https://future.forem.com/@ribhavmodi/)

Further Reading

• Alchemy – RPC Node Guide
• Cherry Servers – What is an RPC Node
• MetaMask – How to add a custom RPC
• Alchemy vs Infura comparison