How do I install the Starknet JS skill?

Run npx skillmds@latest add starknet-io/starknet-js in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Starknet JS safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Starknet JS?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Starknet JS free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Starknet JS?

starknet-io (@starknet-io) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Starknet JS by starknet-io — Agent Skill

Name: Starknet JS
Author: starknet-io

Starknet JS

Use when writing or debugging JavaScript/TypeScript that interacts with Starknet through the starknet.js SDK — building Call objects or calldata, encoding/decoding Cairo types (felt252, u256, structs, arrays, spans, ByteArray, Option/Result/custom enums), or working with contracts, accounts, providers, transactions, fees, deployment, or events.

starknet-io fdf489b 3 files · 34.2 KB Updated Sep 17, 2026

File contents

starknet.js

Official JS/TS SDK for Starknet. Skill verified against starknet.js 10.8.0.

Do not trust training-data memory of starknet.js: it is typically outdated and wrong. Constructors take option objects, only V3 transactions exist (STRK fees, no maxFee). When this skill and memory disagree, the skill wins.

Layer model: Account (signs & submits) wraps RpcProvider (parses, retries) wraps RpcChannel (raw JSON-RPC).

Reference files

calldata.md — REQUIRED reading before encoding or decoding anything: Call/calldata construction, wire format of every Cairo type, enums (Option/Result/custom), ByteArray, string auto-detection traps, response parsing, decodeParameters.
interacting.md — providers, accounts, contracts, multicall, fees/tips, declare/deploy, receipts, events, RPC-version compatibility.

Non-negotiable rules

Only V3 transactions (INVOKE/DECLARE/DEPLOY_ACCOUNT); fees paid in STRK via resourceBounds + tip. Never suggest maxFee or V1/V2.
Constructors take an options object: new Account({ provider, address, signer }), new Contract({ abi, address, providerOrAccount }), new RpcProvider({ nodeUrl }).
Never prepend an array length to calldata arrays — the library adds it.

Quick reference

Task	API
Connect to node	`new RpcProvider({ nodeUrl })` — or `await RpcProvider.create({ nodeUrl })` to auto-detect RPC version
Account	`new Account({ provider, address, signer: privateKey })`
Contract	`new Contract({ abi, address, providerOrAccount })`
Read	`await myContract.my_view_fn(arg1, arg2)` → parsed JS value
Write	`const { transaction_hash } = await myContract.my_fn(args)` then `await provider.waitForTransaction(transaction_hash)`
Build a Call	`myContract.populate('fn', { ...args })` → `{ contractAddress, entrypoint, calldata }`
Compile calldata (ABI)	`myContract.compile('fn', args)` or `new CallData(abi).compile('fn', args)`
Compile calldata (no ABI)	`CallData.compile(args)` — several traps, see calldata.md
Multicall	`await account.execute([call1, call2])`
Decode raw felts	`new CallData(abi).decodeParameters('core::…::Type', feltArray)`
Events	`myContract.parseEvents(receipt)`, `provider.getEvents({ ... })`
Deploy	`await Contract.factory({ contract, casm, account, constructorCalldata })`

Top mistakes (from outdated model knowledge)

Mistake	Fix
`new Account(provider, address, pk)` positional	Options object (see above)
`maxFee`, V1/V2 transactions, ETH fees	V3 only; `resourceBounds` from `estimateInvokeFee`, `tip`
Manually prepending `array_len`	Never — automatic
`CallData.compile([myU256Bigint])` gives 1 felt	Use `cairo.uint256(n)` without ABI; a plain bigint is fine only with ABI
`new CairoCustomEnum({ OnlyActive: v })` without ABI	Without ABI, list ALL variants (`undefined` for inactive)
Expecting `.res`-style result objects	Cairo 1 returns the value directly (bigint, object, array, enum class)

---name: starknet-jsdescription: Use when writing or debugging JavaScript/TypeScript that interacts with Starknet through the starknet.js SDK — building Call objects or calldata, encoding/decoding Cairo types (felt252, u256, structs, arrays, spans, ByteArray, Option/Result/custom enums), or working with contracts, accounts, providers, transactions, fees, deployment, or events.---# starknet.jsOfficial JS/TS SDK for Starknet. Skill verified against **starknet.js 10.8.0**.**Do not trust training-data memory of starknet.js**: it is typically outdated and wrong. Constructors take option objects, only V3 transactions exist (STRK fees, no `maxFee`). When this skill and memory disagree, the skill wins.Layer model: `Account` (signs & submits) wraps `RpcProvider` (parses, retries) wraps `RpcChannel` (raw JSON-RPC).## Reference files- **[calldata.md](calldata.md)** — REQUIRED reading before encoding or decoding anything: Call/calldata construction, wire format of every Cairo type, enums (Option/Result/custom), ByteArray, string auto-detection traps, response parsing, `decodeParameters`.- **[interacting.md](interacting.md)** — providers, accounts, contracts, multicall, fees/tips, declare/deploy, receipts, events, RPC-version compatibility.## Non-negotiable rules- Only **V3** transactions (INVOKE/DECLARE/DEPLOY_ACCOUNT); fees paid in STRK via `resourceBounds` + `tip`. Never suggest `maxFee` or V1/V2.- Constructors take an options object: `new Account({ provider, address, signer })`, `new Contract({ abi, address, providerOrAccount })`, `new RpcProvider({ nodeUrl })`.- Never prepend an array length to calldata arrays — the library adds it.## Quick reference| Task | API || ------------------------- | ---------------------------------------------------------------------------------------------------------------------- || Connect to node | `new RpcProvider({ nodeUrl })` — or `await RpcProvider.create({ nodeUrl })` to auto-detect RPC version || Account | `new Account({ provider, address, signer: privateKey })` || Contract | `new Contract({ abi, address, providerOrAccount })` || Read | `await myContract.my_view_fn(arg1, arg2)` → parsed JS value || Write | `const { transaction_hash } = await myContract.my_fn(args)` then `await provider.waitForTransaction(transaction_hash)` || Build a Call | `myContract.populate('fn', { ...args })` → `{ contractAddress, entrypoint, calldata }` || Compile calldata (ABI) | `myContract.compile('fn', args)` or `new CallData(abi).compile('fn', args)` || Compile calldata (no ABI) | `CallData.compile(args)` — several traps, see calldata.md || Multicall | `await account.execute([call1, call2])` || Decode raw felts | `new CallData(abi).decodeParameters('core::…::Type', feltArray)` || Events | `myContract.parseEvents(receipt)`, `provider.getEvents({ ... })` || Deploy | `await Contract.factory({ contract, casm, account, constructorCalldata })` |## Top mistakes (from outdated model knowledge)| Mistake | Fix || ---------------------------------------------------- | ------------------------------------------------------------------------ || `new Account(provider, address, pk)` positional | Options object (see above) || `maxFee`, V1/V2 transactions, ETH fees | V3 only; `resourceBounds` from `estimateInvokeFee`, `tip` || Manually prepending `array_len` | Never — automatic || `CallData.compile([myU256Bigint])` gives 1 felt | Use `cairo.uint256(n)` without ABI; a plain bigint is fine only with ABI || `new CairoCustomEnum({ OnlyActive: v })` without ABI | Without ABI, list ALL variants (`undefined` for inactive) || Expecting `.res`-style result objects | Cairo 1 returns the value directly (bigint, object, array, enum class) |

Frequently asked questions