Written contract spec
Functions, roles, events, and invariants in plain English, approved by you before development starts.
The Problem
Once Your Contract Is on Mainnet, Every Bug Has a Price Tag
Most contract failures start before the first line of code. There's no written spec, the tests only check the happy path, and one person holds the keys to everything.
01 · Testing
Tests only cover the happy path with friendly inputs.
Foundry fuzz and invariant tests try hostile inputs and odd call orders.
02 · Admin keys
One laptop holds the key that can pause everything.
Admin roles move to a Safe multisig with a timelock before launch.
03 · Transparency
Unverified source leaves holders guessing what they sign.
Every deployed contract gets verified source on the block explorer.
04 · Upgrades
A live bug means a migration and a public post-mortem.
We decide upfront between immutable code and an audited upgrade proxy.
Your launch is set for Thursday. The contract passed every test your developer wrote, but those tests only check the happy path: one user, normal amounts, nothing hostile. Nobody has tried a reentrant call, a rounding edge, or two deposits in the same block. The key that can pause or upgrade everything lives in a browser wallet on one laptop. The source isn't verified, so holders can't read what they're signing. And once it's live, a bug isn't a quick fix. It's a migration, a public post-mortem, and funds that may not come back.
We start with a written spec: every function, every role, and the invariants that must hold no matter who calls what. Then we build on audited OpenZeppelin components, try to break the code with Foundry fuzz and invariant tests, and run Slither before review. Admin keys move to a Safe multisig with a timelock, and the source is verified on the explorer. Your contract ships tested against attackers, not just against the demo.
Spec before Solidity
Functions, roles, and invariants written down and approved before any contract code exists.
Tested to break
Fuzz and invariant tests throw random inputs and odd call orders at every public function.
Keys you control
Admin roles sit behind a Safe multisig and timelock instead of one developer's wallet.
Our Smart Contract Development Services Process
From Written Spec to Verified Mainnet Contract in Five Clear Steps
You approve the spec before any code exists, see the test results before deployment, and sign the mainnet transaction from your own multisig.
We read your whitepaper, product spec, or existing code and ask what the contract must not allow. You get a short list of risks, a chain recommendation, and a fixed quote. If an audited open-source contract already does the job, we'll tell you before we quote.
What's Included
What You Get From Our Smart Contract Development Company
Every project covers the spec, the Solidity, and tests that try to break it. You also get deploy scripts, verified source, and a handover your team can run alone.
Compare Options
DeveloperLook vs a Freelancer vs a DIY Template
A freelancer can be quick and affordable, and a template works for a plain token. Here is where each one holds up once real funds and admin keys are involved.
| Feature | DeveloperLookBest fit | Freelancer | DIY template |
|---|---|---|---|
| Planning | Written spec with invariants | Often starts from chat messages | Template defaults, no spec |
| Customization | Built to your rules | Built to your rules | Limited to template options |
| Security testing | Fuzz, invariant, and Slither runs | Varies by developer | Only the template's own tests |
| Speed to testnet | 3 to 4 weeks for one contract | Often faster for small jobs | Same day for a standard token |
| Admin key setup | Safe multisig and timelock | Usually the deployer's wallet | Usually the deployer's wallet |
| Support | 30 to 90 days after launch | Depends on availability | Community forums |
| Ownership | Your code, keys, and scripts | Your code | Template license terms apply |
| Cost predictability | Fixed price after the spec | Hourly, can grow | Lowest upfront cost |
DeveloperLook
Freelancer
- Planning
- DeveloperLook: Written spec with invariantsFreelancer: Often starts from chat messages
- Customization
- DeveloperLook: Built to your rulesFreelancer: Built to your rules
- Security testing
- DeveloperLook: Fuzz, invariant, and Slither runsFreelancer: Varies by developer
- Speed to testnet
- DeveloperLook: 3 to 4 weeks for one contractFreelancer: Often faster for small jobs
- Admin key setup
- DeveloperLook: Safe multisig and timelockFreelancer: Usually the deployer's wallet
- Support
- DeveloperLook: 30 to 90 days after launchFreelancer: Depends on availability
- Ownership
- DeveloperLook: Your code, keys, and scriptsFreelancer: Your code
- Cost predictability
- DeveloperLook: Fixed price after the specFreelancer: Hourly, can grow
Projects We've Built
Crypto and NFT Projects We Have Built
Crypto and NFT apps we designed and built, with wallet connection, bidding, and on-chain transaction flows. They show the product side your contracts plug into.
ArtChain NFT Digital Arts Website & Dashboard
- Art
- Crypto & NFT
- Dashboard
PixelVault NFT Marketplace Web Design & Development
- Crypto & NFT
- Dashboard
- Website
NFTIN NFT Marketplace App and Trading Dashboard
- Crypto & NFT
- Dashboard
- Mobile App
CoinSphere Crypto App Design & Development
- Crypto & NFT
- Dashboard
- Mobile App
What Our Clients Say
What Clients Say After Launch
Feedback from teams we have built websites, apps, and integrations for.
We had a pretty specific idea of what we wanted our website to become, but I wasn’t sure how easily we could explain all of it to a development team. There were quite a few moving parts, and we were working toward a deadline, so I expected a few things to get lost along the way. That never really happened. They understood what we were trying to achieve, kept us updated throughout the process, and got everything ready within the agreed timeline. The final site feels much easier to navigate, works beautifully on mobile, and is noticeably smoother for our customers. It was a huge relief seeing the original idea actually turn into the website we had in mind.
The mobile experience is probably my favourite part of the new site. We had spent a lot of time making sure the desktop version looked right, and the team kept pushing us to think about how everything would actually feel on a phone too. They were right. The navigation is clean, the interactions feel natural, and everything we’ve tested so far works exactly as it should. They also went through the links, forms, integrations, and other details more than once before launch, which I really appreciated. And even after going live, we could still reach out when something came up. The whole process felt friendly, organised, and surprisingly straightforward.
What I appreciate most is that the website is actually easy for us to manage now. We can update content ourselves instead of sending a developer a message every time we need to change something small. They also paid attention to the technical SEO side, which mattered to us because we didn’t want a new website to create problems for the traffic we already had. I’ve probably asked more questions than I should have since launch, but every question has been handled patiently and without any fuss. The team is easy to work with, they explain things clearly, and when we need something changed, they focus on getting it done rather than making the process complicated.
1,250+
Projects shipped
10+
Years of experience
Top 3%
Upwork Top Rated Plus
5 stars
Average review score
Want results like these?
Tell us what you are building. You get a reply within 24 hours on business days, then a written estimate.
Work Culture
Why Web3 Founders Trust Us With Their Smart Contracts
Contracts hold other people's money, and they're hard to take back. These habits come from shipping crypto products where every transaction is public and permanent.
Invariants before features
We list what must stay true, like supply matching balances, before writing a function. Every test and review then checks those rules, so new features can't quietly break them.
We try to break it first
Our own tests attack the contract with random inputs, repeated calls, and odd orderings. You'd rather we find the edge case on a testnet than a stranger on mainnet.
Honest about audits
We don't call our own review an audit. For contracts holding serious value, we recommend an independent firm, prepare the audit pack, and fix the findings with you.
Keys stay with you
We deploy from your multisig, not ours, and keep no admin role after handover. Control of the contract sits with your signers from the first block.
Gas you can live with
We measure gas per function in the test suite and cut storage writes where it matters. Your users pay less per transaction, and you see the numbers before launch.
Fixed scope, written down
The approved spec sets the price, so a new idea becomes a change order you can accept or skip. You know the cost before we start, not after.
Overview
What is smart contract development for a Web3 product?
DeveloperLook handles smart contract development for Web3 founders and product teams. We write the spec, build Solidity contracts on OpenZeppelin, and test them with Foundry fuzz and invariant tests. Deployed code is verified, with admin keys behind a Safe multisig. Projects start at $1,300, take 3 to 12 weeks, and the scope is fixed before we build.
DEVELOPERLOOK
Project facts · Smart Contract Development Services
- Service
- Smart contract development services (spec, Solidity build, tests, deployment)
- Typical timeline
- 3 to 4 weeks for one contract, 6 to 12 weeks for a suite and dApp
- Platforms
- Ethereum, Base, Arbitrum, Polygon, BNB Smart Chain, and other EVM chains
- Built with
- Solidity, OpenZeppelin Contracts 5.x, Foundry, Hardhat, Slither, and Safe
- Experience
- 10+ years of development experience and 1,250+ shipped projects
- Post-launch support
- 30, 60, or 90 days, depending on plan
- Communication
- Calls in US, UK, and AU business hours
- Starting price
- From $1,300 USD, fixed scope after a free contract review
Reviewed 22 Oct 2026 by Saimul Islam
Good fit
Founders with a spec and no Solidity team
You have the product mapped out and a launch date set. Now you need to hire Ethereum smart contract developers who write the spec before the code.
Teams taking a contract from testnet to mainnet
Your contract works on Sepolia, but nobody has fuzzed it, the deployer key sits on one laptop, and mainnet is three weeks away.
Product teams adding on-chain features
Your app already has users, and you want escrow, memberships, or rewards enforced on-chain without rebuilding the parts that already work.
Projects launching on more than one chain
You plan to launch on Base and Arbitrum as well as Ethereum, and you want one codebase with addresses, roles, and settings tracked per chain.
Agencies with a new Web3 client
Your agency signed a Web3 client and needs Solidity work behind the scenes, with tests and docs your team can present as its own.
Not a fit
Standard token launch only
You only need a standard ERC-20 or BEP-20 token, maybe with vesting. Our Token Development Services page covers that at a lower starting price.
Lending or vault protocol
You're building a lending market, vault, or staking protocol where the math carries most of the risk. Our DeFi Development Services team scopes that work.
Unsure a blockchain fits
You're not sure a blockchain belongs in your product yet. Start with our Blockchain Consulting Services, which can end with a plain database recommendation.
Budget under $1,300
Your budget is under $1,300, or you only need an unchanged copy of an open-source contract. A no-code token or NFT tool is the cheaper way to do that.
Not sure we're the right fit?
Book a free call or message us. We'll tell you honestly whether we're the right team.
Pricing
Transparent Starting Prices for Smart Contract Development Services
These are starting points in USD. Your final price depends on contract count, upgrade needs, and chain count, and you get a fixed proposal after a free contract review.
For teams that need one contract, such as an NFT, escrow, or membership contract, built from a spec.
$1,300one-time, USD
- Written spec and invariant list
- One Solidity contract on OpenZeppelin
- Fuzz tests at 10,000+ runs per property
- Sepolia or testnet rehearsal
- Verified source and multisig handover
- 30 days of post-launch support
Recommended
For products with up to 4 interacting contracts, upgrade needs, and an audit on the roadmap.
$4,200one-time, USD
- Everything in Single Contract
- Up to 4 interacting contracts
- UUPS or transparent upgrade proxy
- Invariant tests and Slither report
- Timelock and audit preparation pack
- 60 days of post-launch support
For launches that need the contracts, a wallet-connected front end, and more than one chain.
$8,600one-time, USD
- Everything in Contract Suite
- dApp front end with wallet connection
- Event indexer for app data
- Deploys on up to 3 EVM chains
- Third-party audit coordination and fixes
- 90 days of post-launch support
For Agencies
White-Label Blockchain Smart Contract Development Services for Agencies
You own the client relationship. We work as your white-label smart contract development agency, supplying the spec, the Solidity, the tests, and the deploy scripts. Everything ships under your agency name, with docs your team can present.
How the partnership works
White label: your client only ever sees your brand
- Your client
- You, the agency
- DeveloperLook
Share the brief
Send the client's whitepaper, target chain, and launch date, plus any existing contracts.
- Client needs
- You share the details
- Details received
We spec and build
You get a fixed quote, then we write, test, and rehearse the contracts on a testnet.
- Scope and plan
- Proposal to resell
- Your quoteYOUR LOGO
You deliver the launch
Your team presents the verified contracts and runbook under your brand, with our support.
- Done by our team
- Your brand on it
- Handed to your clientDone
Partner with DeveloperLookDelivered under your brand
Stay client-facing
Your name on the spec, test report, and runbook, and we stay off client calls.
Predictable delivery
Fixed scope per contract, with test and testnet milestones dated in the plan.
Senior Solidity engineering
Contracts built on OpenZeppelin and tested with Foundry fuzz and invariant runs.
Flexible capacity
Take on Web3 clients without hiring a full-time Solidity developer.
The Right Technology for Your Project
Technology Stack
We use the tools the Ethereum ecosystem relies on for testing and deployment, so any auditor or future developer can pick up the code.
- Solidity
- OpenZeppelin
- Foundry
- Hardhat
- Slither
- Ethereum
- Base
- Arbitrum
- Polygon
- BNB Smart Chain
- Safe multisig
- Timelock
- Chainlink
- Explorer verification
Next.js
TypeScript- wagmi
- ethers.js
Node.js- GitHub Actions
FAQ
Frequently Asked Questions
Straight answers on cost, timelines, deployment, upgrades, cross-chain builds, and audits.
Saimul IslamFounder & CEO, DeveloperLookStill have questions?
Send a message or book a call with the team.
Smart contract development with DeveloperLook starts at $1,300 for one contract built from a written spec, fuzz-tested, and deployed with verified source. A suite of up to 4 interacting contracts with an upgrade proxy starts at $4,200. Contracts plus a dApp on up to 3 chains start at $8,600. Smart contract developer cost depends mostly on how many contracts interact and how much value they hold. The free review ends in a fixed quote.
Most single contracts take 3 to 4 weeks from the free review to mainnet. A suite with an upgrade proxy and invariant tests takes 6 to 9 weeks. Adding a dApp and more chains stretches it to about 12 weeks. An independent audit adds its own queue time, so we book it from the spec stage instead of waiting for the code.
A smart contract developer writes, tests, and deploys code that runs on a blockchain, most often in Solidity for Ethereum and other EVM chains. The job is closer to building financial infrastructure than a website. The code is public, hard to change, and holds value. If you hire smart contract developers, ask to see their test suites before their portfolios.
We develop a smart contract in five steps, from a free review to the mainnet launch. In between come a written spec with invariants, the Solidity build with unit tests, and fuzz testing with a testnet rehearsal. You approve the spec before any code exists, and every later step ends with a test report or a testnet address you can check.
We write smart contracts in Solidity, starting from audited OpenZeppelin components for tokens, access control, and upgrades instead of hand-rolling them. Each public function checks its inputs first, updates state before any external call, and emits events your app can index. We keep contracts small and single-purpose, which makes them cheaper to test and easier for an auditor to read.
We deploy with a script, not by hand, so every chain gets the same steps in the same order. The script runs first on Sepolia or the chain's testnet, then on mainnet from your Safe multisig. Afterward we verify the source on the block explorer, move admin roles to your signers, and record every address in a shared address book.
Cross-chain smart contract development works best with one codebase, deterministic addresses, and an established messaging protocol such as Chainlink CCIP instead of a homemade bridge. We test the failure paths: a message that arrives late, twice, or not at all. Each chain gets its own settings file for gas tokens, oracles, and signers, so a Base deploy can't inherit Ethereum's values by mistake.
Only if it was built to be upgradeable. An immutable contract can't change, so a fix means deploying a new version and moving users across. An upgradeable one sits behind a proxy, such as OpenZeppelin's UUPS or transparent pattern, so approved signers can swap the logic later. We help you choose before the build. Upgrades add flexibility, but they also ask holders to trust whoever holds the upgrade key.
No. Nobody should audit their own code, so we test hard, run Slither, and prepare an audit pack with the spec, test results, and known risks. For contracts that will hold meaningful value, we recommend an independent audit firm, coordinate the schedule, and fix their findings with you before launch. That keeps the audit honest and the launch date realistic.
You own everything: the repository, the deployment scripts, the verified contracts, and every admin role. We deploy from your Safe multisig and keep no keys or roles after handover. Your plan includes 30, 60, or 90 days of post-launch support for questions and fixes to our own work. Longer support is available as a separate agreement.
Saimul IslamFounder & CEO, DeveloperLookStill have questions?
Send a message or book a call with the team.
Free 30-min callGoogle Meet
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