Senior Software Security Engineer (f/m)
Status
Paris, France
Full time
Office
Compensation is not specified
Role
Security Engineer
Description
We are a forward-thinking team of innovators, dedicated to revolutionizing digital ownership in a dynamic world. Our mission goes beyond commercial interests as we strive to unlock authentic freedom through our cutting-edge products.
At Ledger, founded in 2014, we are the global frontrunners in digital assets and Web3 technologies. With our headquarters in Paris and Vierzon, and additional offices across various countries, our team of over 700 professionals is committed to enabling secure transactions and management of crypto assets for individuals and businesses worldwide.
If you join us as a security engineer focused on consumer services, you will play a crucial role in ensuring the robustness and integrity of our products and ecosystem. Your daily tasks will involve identifying vulnerabilities, developing offensive security strategies, and conducting security assessments to uphold our industry leadership.
Responsibilities:
- Collaborate closely with development teams to detect and remedy vulnerabilities in backend services and APIs.
- Engage in ongoing research to stay informed about advanced offensive security methods.
- Create tools and exploits for our products and provide solutions for identified issues.
- Conduct security assessments and threat evaluations for Ledger's services ecosystem including DeFi services.
- Encourage secure coding practices within the engineering teams and present findings at global conferences.
Requirements:
- Prior experience in security, especially in blockchain security, is advantageous.
- Proficiency in applied cryptography with a basic understanding of financial services.
- Self-motivated with a keen interest in evolving security landscapes.
Technical Skillset:
- Advanced experience in web/backend penetration testing.
- Proficiency in secure programming using Python, Rust, and basic knowledge of Scala.
- Familiarity with Kubernetes and cloud infrastructure.
- Knowledge of exploitation techniques and relevant preventive measures.
- Ability to automate security analysis and design secure architectures.
Perks:
- Equity opportunities through stock options to benefit from the company's growth.
- Hybrid work policy for flexible work arrangements.
- Social events, annual company outings, snacks, and drinks for a vibrant work environment.
- Comprehensive health insurance coverage including medical, dental, and vision care.
- Personal development and fitness support.
- Generous vacation time with additional leave including national holidays.
- Access to high-performance office equipment and gadgets.
- Transportation reimbursement and employee discounts on all products.
We guarantee equal opportunities for all candidates throughout the recruitment process, irrespective of gender, ethnicity, religion, sexual orientation, social status, disability, or age.
Skills Required
Ledger
Website
www.ledger.comCompany size
Not specified
Location
United States
Description
Not specified
Status
NTC IT Corp.
Remote Data Entry & Internet Research Assistant (Beginner Friendly)
Remote, USA
Remote, USA
Part time
Remote
We are an international IT and digital support company looking for new remote assistants.
The job is very simple and beginner friendly. No special experience is required. Training and instructions will be provided.
Your tasks may include:
• Checking basic online information
• Testing simple crypto or digital tools
• Completing small verification tasks
• Following step-by-step instructions
• Helping our team with easy online activities
Most tasks take 5–20 minutes to complete.
Payment starts from $8–$15 per task. More tasks and higher payments are available for active workers.
Requirements:
• Basic English understanding
• Smartphone or computer
• Internet connection
• Responsibility and ability to follow instructions
This is a flexible remote opportunity. You can work from anywhere and choose your working hours.
Long-term cooperation is available for reliable workers.
The job is very simple and beginner friendly. No special experience is required. Training and instructions will be provided.
Your tasks may include:
• Checking basic online information
• Testing simple crypto or digital tools
• Completing small verification tasks
• Following step-by-step instructions
• Helping our team with easy online activities
Most tasks take 5–20 minutes to complete.
Payment starts from $8–$15 per task. More tasks and higher payments are available for active workers.
Requirements:
• Basic English understanding
• Smartphone or computer
• Internet connection
• Responsibility and ability to follow instructions
This is a flexible remote opportunity. You can work from anywhere and choose your working hours.
Long-term cooperation is available for reliable workers.
Payment in Crypto
Hazel Thomas
Web3 + Supabase Developer Needed to Complete BSC Testnet Waitlist & Staking Platform
Washington, USA
Washington, USA
Part time
Remote
📌 Job Description
We are building a production-ready Web3 waitlist and dashboard platform using Next.js 15 (App Router), BSC Testnet, Supabase, and Wagmi v2.
The core architecture, database schema, and feature roadmap are already defined. We are looking for an experienced developer to complete, polish, and harden the project.
This is not a prototype — the goal is a fully working, deployable system with clean code, security best practices, and proper Web3 UX.
🧩 Project Overview
The platform includes:
Wallet-based user registration (BSC Testnet only)
Automatic network detection & switching
Supabase-backed user management
Automatic virtual card generation (Bronze / Silver / Gold)
Token staking system with transaction logging
Referral system with rewards tracking
Dashboard with analytics & history
X (Twitter) OAuth integration
Discord bot with XP & invite tracking
A detailed README and database schema are already prepared.
✅ Responsibilities
You will be responsible for:
Completing and stabilizing the Next.js App Router implementation
Finalizing wallet connection & network enforcement (Chain ID 97)
Ensuring Supabase RLS policies are correct and secure
Implementing or completing:
Staking flows (stake, unstake, claim, emergency withdraw)
Referral tracking & reward logic
Dashboard analytics & transaction history
Finalizing X (Twitter) OAuth integration
Reviewing and improving overall code quality & structure
Fixing bugs, edge cases, and UX issues
Preparing the app for Railway deployment
(Bonus) Improving performance and Web3 UX
🛠 Tech Stack (Must-Have Experience)
Required:
Next.js 14/15 (App Router)
TypeScript
Wagmi v2 + WalletConnect
EVM chains (BSC preferred)
Supabase (Postgres, RLS, triggers, SQL functions)
Tailwind CSS
Web3 transaction handling & logging
Nice to Have:
Discord bot development (Node.js)
OAuth 2.0 (X / Twitter)
Smart contract interaction (staking contracts)
Framer Motion
shadcn/ui / Radix UI
🔒 Security Expectations
You must be comfortable with:
Wallet validation & chain enforcement
Preventing self-referrals & abuse
Transaction hash uniqueness checks
Secure handling of OAuth tokens
Supabase RLS & role-based access
📦 Deliverables
Fully working, deployable application
Clean, documented codebase
Verified Supabase schema & policies
Functional staking & referral systems
Deployment-ready build (Railway)
Basic handover documentation
⏳ Timeline
Estimated duration: 2–4 months
Start: Immediately
Potential for long-term collaboration
💰 Budget
Open to fixed-price or hourly
Please include:
Your estimated timeline
Relevant Web3 / Next.js projects
Any questions or suggestions to improve the system
🧠 How to Apply
When applying, please answer:
Have you built production Web3 apps with Next.js + Wagmi before?
Have you worked with Supabase RLS & SQL triggers?
Share 1–3 relevant projects (GitHub or live links)
What risks or improvements do you see in this architecture?
Generic proposals will be ignored.
We are building a production-ready Web3 waitlist and dashboard platform using Next.js 15 (App Router), BSC Testnet, Supabase, and Wagmi v2.
The core architecture, database schema, and feature roadmap are already defined. We are looking for an experienced developer to complete, polish, and harden the project.
This is not a prototype — the goal is a fully working, deployable system with clean code, security best practices, and proper Web3 UX.
🧩 Project Overview
The platform includes:
Wallet-based user registration (BSC Testnet only)
Automatic network detection & switching
Supabase-backed user management
Automatic virtual card generation (Bronze / Silver / Gold)
Token staking system with transaction logging
Referral system with rewards tracking
Dashboard with analytics & history
X (Twitter) OAuth integration
Discord bot with XP & invite tracking
A detailed README and database schema are already prepared.
✅ Responsibilities
You will be responsible for:
Completing and stabilizing the Next.js App Router implementation
Finalizing wallet connection & network enforcement (Chain ID 97)
Ensuring Supabase RLS policies are correct and secure
Implementing or completing:
Staking flows (stake, unstake, claim, emergency withdraw)
Referral tracking & reward logic
Dashboard analytics & transaction history
Finalizing X (Twitter) OAuth integration
Reviewing and improving overall code quality & structure
Fixing bugs, edge cases, and UX issues
Preparing the app for Railway deployment
(Bonus) Improving performance and Web3 UX
🛠 Tech Stack (Must-Have Experience)
Required:
Next.js 14/15 (App Router)
TypeScript
Wagmi v2 + WalletConnect
EVM chains (BSC preferred)
Supabase (Postgres, RLS, triggers, SQL functions)
Tailwind CSS
Web3 transaction handling & logging
Nice to Have:
Discord bot development (Node.js)
OAuth 2.0 (X / Twitter)
Smart contract interaction (staking contracts)
Framer Motion
shadcn/ui / Radix UI
🔒 Security Expectations
You must be comfortable with:
Wallet validation & chain enforcement
Preventing self-referrals & abuse
Transaction hash uniqueness checks
Secure handling of OAuth tokens
Supabase RLS & role-based access
📦 Deliverables
Fully working, deployable application
Clean, documented codebase
Verified Supabase schema & policies
Functional staking & referral systems
Deployment-ready build (Railway)
Basic handover documentation
⏳ Timeline
Estimated duration: 2–4 months
Start: Immediately
Potential for long-term collaboration
💰 Budget
Open to fixed-price or hourly
Please include:
Your estimated timeline
Relevant Web3 / Next.js projects
Any questions or suggestions to improve the system
🧠 How to Apply
When applying, please answer:
Have you built production Web3 apps with Next.js + Wagmi before?
Have you worked with Supabase RLS & SQL triggers?
Share 1–3 relevant projects (GitHub or live links)
What risks or improvements do you see in this architecture?
Generic proposals will be ignored.
Payment in Crypto
lucas martin
Senior Web3 / Crypto Trading Platform Developer
Full time
Remote
PumaPulse is launching a new standalone domain focused on building professional-grade crypto trading platforms and on-chain trading tools. We are seeking an experienced freelance Web3 developer to help design, build, and evolve a scalable trading product with commercialization potential.ResponsibilitiesDevelop crypto trading tools, bots, or SaaS platformsIntegrate with DEXs and on-chain protocols (e.g., Solana, Ethereum)Implement real-time blockchain data monitoring and trade executionEnsure security, performance, and MEV-aware designCollaborate on product roadmap, strategy, and future featuresRequirementsStrong experience in Web3 and DeFi developmentProven work with crypto trading bots or on-chain trading systemsExperience with at least one major blockchain ecosystemSolid understanding of smart contract interaction and security best practicesAbility to deliver production-ready code and communicate clearlyNice to HaveExperience productizing tools into SaaS platformsBackground in advanced trading strategies or MEVPrior work with VC-backed or early-stage Web3 projectsEngagementFreelance / contract roleCompetitive compensation based on experiencePotential for long-term collaborationApply with relevant Web3 projects, GitHub links, and availability.
Payment in Crypto
Austin Smart
Fullstack Developer Needed for Web3 Prediction Market Platform
Brooklyn, USA
Brooklyn, USA
Full time
Remote
Summary
We're looking for an experienced Blockchain / Full-Stack Developer to help build a production-ready MVP for a Web3 prediction marketplace.
We’ve already built a basic UI prototype using vibe coding. The goal now is to turn this prototype into a functional, scalable dApp with clean architecture and solid Web3 fundamentals.
This is not a tutorial or experimental project — We’re looking for someone who has real experience shipping blockchain/web3 products.
What You’ll Do
Review and improve an existing UI prototype
Build smart contract logic for a prediction marketplace MVP
Integrate blockchain functionality with the frontend
Develop backend / API logic as needed
Ensure clean, maintainable, production-ready code
Collaborate on product decisions and MVP scope
Tech Stack (Preferred)
Frontend: Next.js / React
Backend: Node.js
Blockchain: Solidity / Rust
Experience with non-EVM chains is a plus (open to discussion)
What We're Looking For
- Strong experience in Blockchain & Web3 development
- Proven ability to build production-ready dApps
- Proficiency in Next.js, React, and Node.js
- Experience designing and shipping MVPs
- Good communication and ability to work independently
Nice to Have
- Previous work on prediction markets, DeFi, or marketplaces
- Experience taking projects from prototype to launch
- Performance, security, and scalability mindset
How to Apply
Please include:
- A brief summary of your Web3 experience
- Links to previous dApps or blockchain projects
- Your preferred tech stack and availability
If you’re an expert in blockchain and Web3 and enjoy building real products from early prototypes, We’d love to hear from you.
We're looking for an experienced Blockchain / Full-Stack Developer to help build a production-ready MVP for a Web3 prediction marketplace.
We’ve already built a basic UI prototype using vibe coding. The goal now is to turn this prototype into a functional, scalable dApp with clean architecture and solid Web3 fundamentals.
This is not a tutorial or experimental project — We’re looking for someone who has real experience shipping blockchain/web3 products.
What You’ll Do
Review and improve an existing UI prototype
Build smart contract logic for a prediction marketplace MVP
Integrate blockchain functionality with the frontend
Develop backend / API logic as needed
Ensure clean, maintainable, production-ready code
Collaborate on product decisions and MVP scope
Tech Stack (Preferred)
Frontend: Next.js / React
Backend: Node.js
Blockchain: Solidity / Rust
Experience with non-EVM chains is a plus (open to discussion)
What We're Looking For
- Strong experience in Blockchain & Web3 development
- Proven ability to build production-ready dApps
- Proficiency in Next.js, React, and Node.js
- Experience designing and shipping MVPs
- Good communication and ability to work independently
Nice to Have
- Previous work on prediction markets, DeFi, or marketplaces
- Experience taking projects from prototype to launch
- Performance, security, and scalability mindset
How to Apply
Please include:
- A brief summary of your Web3 experience
- Links to previous dApps or blockchain projects
- Your preferred tech stack and availability
If you’re an expert in blockchain and Web3 and enjoy building real products from early prototypes, We’d love to hear from you.
Payment in Crypto
Emir Hammami
Looking for a blockchain developer
Whiteman Air Force Base, USA
Whiteman Air Force Base, USA
Full time
Remote
We are looking for a skilled Full-Stack Blockchain Developer to help maintain, improve, and extend the RaiseHive platform. This role involves working across the frontend, backend, and smart contract layers to ensure a stable, secure, and scalable Web3 application.
The ideal candidate has hands-on experience with React, Node.js, Ethereum smart contracts, and real-world Web3 integrations.
Framework: React 18.2 (Vite 3)
Styling: Tailwind CSS 3.4, NextUI
Animations: Framer Motion
Web3: Thirdweb SDK v4, Ethers.js v5
Routing: React Router DOM v6
State Management: React Context API
Libraries: React Markdown, React Image Gallery, Replyke (comments), React Toastify
Runtime: Node.js
Framework: Express.js
Database: MongoDB Atlas (Mongoose ODM)
Email: Nodemailer
Scheduling: Node-cron
Logging: Pino
Network: Ethereum
Smart Contracts: Solidity ^0.8.19
Development Tools: Hardhat
Libraries: OpenZeppelin, Thirdweb Contracts
Wallet Integration: MetaMask
Frontend
Strong proficiency in React (hooks, context, routing)
Experience with Vite or modern build tools
Solid knowledge of Tailwind CSS and responsive design
Experience using component libraries (NextUI, Material UI, etc.)
Backend
Strong experience with Node.js and Express
Proficiency with MongoDB and Mongoose
REST API design and implementation
Environment configuration and deployment awareness
Blockchain & Web3
Hands-on Ethereum development experience
Solidity smart contract development
Experience with Ethers.js / Thirdweb SDK
Understanding of smart contract security and gas optimization
MetaMask wallet integration and transaction handling
General
JavaScript (ES6+)
Git version control
Async programming and debugging skills
Strong problem-solving ability
The ideal candidate has hands-on experience with React, Node.js, Ethereum smart contracts, and real-world Web3 integrations.
Framework: React 18.2 (Vite 3)
Styling: Tailwind CSS 3.4, NextUI
Animations: Framer Motion
Web3: Thirdweb SDK v4, Ethers.js v5
Routing: React Router DOM v6
State Management: React Context API
Libraries: React Markdown, React Image Gallery, Replyke (comments), React Toastify
Runtime: Node.js
Framework: Express.js
Database: MongoDB Atlas (Mongoose ODM)
Email: Nodemailer
Scheduling: Node-cron
Logging: Pino
Network: Ethereum
Smart Contracts: Solidity ^0.8.19
Development Tools: Hardhat
Libraries: OpenZeppelin, Thirdweb Contracts
Wallet Integration: MetaMask
Frontend
Strong proficiency in React (hooks, context, routing)
Experience with Vite or modern build tools
Solid knowledge of Tailwind CSS and responsive design
Experience using component libraries (NextUI, Material UI, etc.)
Backend
Strong experience with Node.js and Express
Proficiency with MongoDB and Mongoose
REST API design and implementation
Environment configuration and deployment awareness
Blockchain & Web3
Hands-on Ethereum development experience
Solidity smart contract development
Experience with Ethers.js / Thirdweb SDK
Understanding of smart contract security and gas optimization
MetaMask wallet integration and transaction handling
General
JavaScript (ES6+)
Git version control
Async programming and debugging skills
Strong problem-solving ability
Payment in Crypto