ChainGreets — Documentation

Overview

⬡

ChainGreets v1.1

Multi-chain · EVM · No backend

ChainGreets is a multi-chain EVM DApp for sending daily on-chain greetings (GM / GN) across testnets and mainnets. Each action is limited to 1 per chain per day per wallet.

GM and GN calls go directly to the deployed smart contract via gm() or gn(). The daily limit is enforced onchain via a dayIndex (block.timestamp / 86400, UTC). A GM or GN event is emitted and indexed by Blockscout. Currently 8 testnets and 15 mainnets have SCs deployed.

Deployed SCs — testnets GM & GN

Chain	ChainId	SC Address	Deploy Block	GM SC	GN SC
Ethereum Sepolia	11155111	0xcF9c…8FA / 0x5De3…66D7	7 800 000	✓	✓
Base Sepolia	84532	0x5117…300 / 0xcF9c…8FA	22 000 000	✓	✓
Arb Sepolia	421614	0xb691…635 / 0xa5c8…C77	120 000 000	✓	✓
OP Sepolia	11155420	0xb691…635 / 0xa5c8…C77	24 000 000	✓	✓
Soneium Minato	1946	0x84A7…C10 / 0xc716…b7A	7 500 000	✓	✓
Robinhood Testnet	46003	0x5117…300 / 0xcF9c…8FA	50 000	✓	✓
Arc Testnet	5184542	0xa5c8…C77 / 0x73A3…e23	30 000 000	✓	✓
MegaETH Testnet v2	6343	0xb691…635 / 0x84A7…C10	13 521 901	✓	✓
Tempo Testnet	0xa5bf	not deployed	—	pending	pending

🌐

Deployed SCs — mainnets

GM 0xb691…635 · GN 0xAC39…6Db

Chain	ChainId	GM Block	GN Block	GM SC	GN SC
Base	8453	43 357 634	43 359 071	✓	✓
Arbitrum	42161	441 763 485	441 766 590	✓	✓
Ethereum	1	24 657 017	24 657 073	✓	✓
Soneium	1868	20 186 110	20 186 452	✓	✓
MegaETH	4326	10 710 021	10 710 692	✓	✓
Unichain	130	42 758 727	42 759 393	✓	✓
Ink	57073	40 008 730	40 009 391	✓	✓
OP	10	148 954 205	148 954 537	✓	✓
Katana	735607	26 764 423	26 765 140	✓	✓
Linea	59144	29 704 156	29 704 318	✓	✓
HyperEVM	999	29 741 268	29 741 904	✓	✓
Monad	143	61 410 454	61 411 446	✓	✓
Plume	98866	54 376 507	54 376 639	✓	✓
Superposition	55244	2 884 879	2 884 883	✓	✓
Polygon	137	84 195 365	84 195 266	✓	✓

Pending deployments — next steps

Priority	Action	Chains	Files impacted
Planned	GM + GN SC	Tempo Testnet	actions.jsgm-feed.jsgm-dashboard.html
Next	Leaderboard multi-chain	All chains	gm-dashboard.html
Next	NFT Mint on GM/GN	TBD	New contract + UI

SC Integration Guide — adding a new chain

⚠️

After each SC deployment, retrieve the exact contract creation block from the explorer (Contract Creator → block #). Never leave deployBlock: 0 in production.

☀️

Add GM SC on a testnet

e.g. Tempo Testnet

1

js/actions.js — GM_CONTRACTS Add to the GM_CONTRACTS object:
'0xa5bf': '0xADRESSE_SC', // Tempo Testnet

2

js/gm-feed.js — TESTNET_SC Add to the TESTNET_SC object (key = decimal ethChainId):
CHAIN_ID_DEC: { contract, blockscoutBase, explorerTxBase, deployBlock, rpcUrl, rpcBlockWindow }

3

js/gm-feed-events.js — GM_EVENT_CHAINS Add an entry to the GM_EVENT_CHAINS array with enabled: true.

4

gm-dashboard.html — CHAINS Add to the local CHAINS array in the dashboard.

5

js/chains-feed.js — FEED_CHAINS Add the testnet entry (with test:true and Blockscout URL in exp).

Transaction Anatomy

⛓

GM / GN via Smart Contract

testnets & mainnets

Field	Value
`to`	Deployed SC address for the chain
`value`	Protocol fee in native token — see fee table below
`data (GM)`	Selector `gm()` = `0xc0129d43`
`data (GN)`	Selector `gn()` = `0x3118f543`
`event GM`	`GM(address indexed sender, uint256 indexed dayIndex, uint256 timestamp, uint256 feePaid)`
`event GN`	`GN(address indexed sender, uint256 indexed dayIndex, uint256 timestamp, uint256 feePaid)`
`dayIndex`	`block.timestamp / 86400` — UTC, resets at midnight
`limit`	1 GM and 1 GN per wallet per chain per day — enforced onchain

Feed & Dashboard — data sources

📡

Fetch strategy by mode

Situation	Primary source	Fallback	API Key
GM / GN SC events (testnets)	Blockscout `getLogs` (topic0+topic2+dayIndex)	ethers.js RPC	Not required
Dashboard — chains with Blockscout	Blockscout API v2 `/addresses/{SC}/transactions`	—	Not required
Dashboard — chains without Blockscout API	RPC `eth_getLogs` direct	—	Not required

⚡

In-memory cache

Each fetch is cached in memory for 45 seconds, keyed by chainId:msgFilter:timeFilter (gm-feed) or chainKey (gm-feed-events). The cache is invalidated on chain or period change.

For long periods (1 month, all time), fetches are batched in groups of 5 dayIndex in parallel with progress display.

Protocol Fees

💰

Per-chain config — FEE_CONFIG

chains-index.js

Chain(s)	Token	Amount	~USD
ETH testnets	ETH (testnet)	`0.0000123 ETH`	—
ETH mainnets (Base, Arb, ETH, OP, Linea…)	ETH	`0.00000123 ETH`	~$0.003
HyperEVM	HYPE	`0.000123 HYPE`	<$0.01
Plume	PLUME	`0.123 PLUME`	<$0.01
Monad	MON	`0.123 MON`	<$0.01
Arc Testnet	USDC (native)	`0.0123 USDC`	—
Tempo Testnet	pathUSD	`0.0123 pathUSD`	—

All mainnet fees are set to stay under $0.01 — approximately the cost of gas alone. Fees cover hosting, domain, and development tooling costs.

File Structure

File	Role	SC update needed
`js/chains-index.js`	CHAINS, FEE_CONFIG, faucets — home page	Yes — feeConfig + remove chain
`js/actions.js`	GM/GN SC routing, `GM_CONTRACTS` + `GN_CONTRACTS`	Yes — always
`js/gm-feed.js`	GM/GN SC event feed via Blockscout getLogs + RPC fallback	Yes — TESTNET_SC
`js/gm-feed-events.js`	SC events feed, D3 graph, period filters	Yes — GM_EVENT_CHAINS
`js/chains-feed.js`	FEED_CHAINS for gm-feed + dashboard	Yes — add testnet/mainnet
`gm-dashboard.html`	SC events analytics dashboard (D3, Chart.js)	Yes — local CHAINS
`js/ui.js`	Chain card rendering, Done today badge	No
`js/wallet.js`	EIP-6963, connect, switch, add chain	No
`js/state.js`	localStorage: streak, TX history, daily limits	No
`js/modal.js`	Success modal after GM/GN	No
`css/style.css`	Global design system (tokens, components)	No
`css/gm-feed.css`	Feed-specific styles	No

ChainGreets — Docs