Senior Java Blockchain Engineer

Java + BTC + ETH + Solana + TRON

Full-time, EU timezone (±)

Location: Europe (preferred)

Project Overview

Building an internal wallet technology platform for custodial operations across Bitcoin, Ethereum, Solana, and TRON. The goal is to replace a fragmented setup of multiple vendor-specific tools with a unified, client-owned stack — consolidating policy engines, wallet registries, and governance frameworks into a single system.

Platform scope: policy and governance · wallet management · transaction construction and execution · signing coordination

Responsibilities

Design and develop a unified custodial wallet platform from the ground up

Build and maintain wallet management, transaction construction, and signing coordination modules

Implement policy and governance layers for multi-chain operations

Integrate blockchain protocols: Bitcoin, Ethereum, Solana, TRON

Ensure security, scalability, and reliability of the custody infrastructure

Consolidate existing vendor-specific tools into a single client-owned stack

Requirements (Must-have)

Strong hands-on Java development experience in production environments

Proven experience with blockchain protocols — BTC, ETH, Solana, TRON

Deep understanding of wallet infrastructure: key management, signing flows, transaction lifecycle

Experience building or integrating custodial / non-custodial wallet systems

Solid understanding of cryptographic primitives (signing schemes, key derivation)

EU timezone availability, full-time commitment

Nice to Have

Experience with HSM or MPC-based signing coordination

Familiarity with multi-chain wallet registries

Prior work on fintech or crypto custody platforms

Tech Stack

Java · Bitcoin · Ethereum · Solana · TRON · Wallet Infrastructure

Hiring Process

Intro call → Technical discussion → Offer

Start: ASAP

Duration: Long-term (8+ months)