Blockchain Development
Netsujo Inc. is a Kyoto-based Web3 and blockchain development company supporting Ethereum/EVM, Cosmos SDK, and Symbol. We take projects from design through implementation and operation, with indicative pricing of JPY 500,000–2,000,000 for requirements definition and JPY 2,000,000–8,000,000 for PoC development.
Why clients choose Netsujo
- One team from design through audit response
- The same team handles contract design, coordination with an external audit firm, remediation of findings, and production deployment. Audits themselves are performed by a third-party specialist firm; Netsujo handles the implementation and response.
- Chain Up KYOTO working group member
- We joined the "Chain Up KYOTO" working group on March 10, 2026, and participate in discussions on the real-world implementation of Web3 and blockchain through study sessions and project reviews.
- Same team from PoC to production
- Contracts and requirements validated in PoC carry straight into production implementation, avoiding hand-off loss and re-interviewing for requirements.
Supported technology stack: EVM chains (Ethereum, Polygon, Arbitrum, etc.), non-EVM chains (Symbol, Cosmos SDK, etc.), L2, and off-chain integration; Solidity, TypeScript, Next.js, React Native, and AWS. We support the full path from requirements to security-audit response and operation.
Development process
- Requirements definition — business-problem framing, judging whether Web3 applies, use-case design
- Technology and architecture selection — choosing among Ethereum, Cosmos SDK, and Symbol; on-chain/off-chain policy and security requirements
- Smart contract development — Solidity/CosmWasm implementation, testing, security audit; token-economy and governance design
- Frontend and backend development — wallet-connected UI, admin console, API, with UX built for Web2 users too
- Testing, deployment, and operation — testnet validation, mainnet deployment, monitoring, upgrades, and incident response
Chain comparison
| Chain | Characteristics | Typical use case | Language |
|---|---|---|---|
| Ethereum / EVM | Largest ecosystem; L2 options (Polygon, Arbitrum, etc.) | NFTs, DeFi, token issuance, DAOs | Solidity |
| Cosmos SDK | Purpose-built chains; IBC interoperability | Custom chains, cross-chain integration | Go / CosmWasm |
| Symbol | API-based, fast to build on; multisig built in | Certification/authentication, supply chain, regional currency | REST API |
Pricing and duration
| Tier | Scope | Duration |
|---|---|---|
| Small — PoC / prototype | Standalone smart contract, minimal validation prototype | 1–3 months |
| Standard — MVP | Contract + frontend + admin console; minimal production-ready build | 3–6 months |
| Enterprise — full-scale build | Multiple contracts, external system integration, security audit, operation | 6 months+ |
A standalone smart contract typically runs JPY 1,000,000–5,000,000; a full dApp with token economy, front/back end, and operations can run JPY 10,000,000–30,000,000. External security audits are a separate JPY 1,000,000–5,000,000. We recommend narrowing scope first and investing in stages from a PoC.
Frequently asked questions
- How is Web3 development different from ordinary system development?
- Web3 is a decentralized system built on a blockchain rather than a company-managed server, users are identified by wallet and private key rather than ID/password, and a smart contract is difficult to change once deployed — which raises the stakes on design and security.
- How far does security coverage go?
- We support smart-contract design review and audit coordination, token-economy design, multisig and permission design, private-key management policy, and security design for DAO governance and AI×blockchain projects, from planning through operation.
- Which chain should we use — Ethereum, Cosmos, or Symbol?
- It depends on the goal: Ethereum/L2 for the largest developer and user base (NFTs, DeFi, global reach); Cosmos SDK for building an independent chain or interoperating with others; Symbol for domestic Japanese use cases, low-cost token issuance, and integration with existing back-office systems. We evaluate against use case, regulatory fit, operating cost, and liquidity.
- How long does smart contract development take?
- A simple ERC-20 token takes 1–2 weeks, an ERC-721/1155 NFT 2–4 weeks, and complex logic (staking, governance, a DEX) 1–3 months. Including frontend, testing, and a security audit, budget roughly 2–6 months in total.
- Is a security audit mandatory?
- We strongly recommend an external audit for any contract handling real assets (tokens, NFTs, DeFi, payments, credential proofs). Deployed contracts are hard to fix, and unaudited projects have suffered multi-million-dollar losses in the past. We combine internal review with introductions to audit firms such as OpenZeppelin, CertiK, and Quantstamp, building security in from the PoC stage.
Smart contract, Web3 app, and mobile app development enquiries. The first 30-minute consultation is free.
Talk to us about development