{"id":3809934,"url":"https://alion.io/job/4soft-senior-blockchain-engineer","title":"Senior Blockchain Engineer","company":{"id":4465305,"name":"4soft","domain":"4soft.co","url":"https://alion.io/company/4soft-2","size_band":"51-200","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":null,"truth_index":null},"role":"Web3","role_family":"Web3","seniority":"senior","employment_type":"contractor","work_mode":"remote","remote_scope":"stated_countries","remote_scope_basis":"board_field","remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Wrocław, Poland","Warsaw, Poland","Kraków, Poland"],"countries":["PL"],"hiring_countries":["PL"],"hiring_countries_total":1,"salary":{"min":27000,"max":32000,"currency":"PLN","period":"month","gross":null,"usd_annual":98100},"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"DeFi","optional":false},{"name":"Smart Contracts","optional":false},{"name":"Solidity","optional":false}],"status":"live","first_seen_at":"2026-11-05T13:23:12Z","employer_posted_date":null,"last_verified_at":"2026-11-05T13:23:12Z","board_verified":false,"closed_at":null,"days_open":2,"trust":{"level":"not_scored","repost_count":null,"flags":[],"days_open":2},"description":"We've been building digital products for over 10 years, with a strong focus on Blockchain-based applications. At 4soft, people come first - it's our team of passionate technologists that enables us to work with international clients and deliver innovative solutions. We believe in transparency, effective teamwork, and achieving real business outcomes for those we serve.\nAs a Senior Blockchain Engineer, you’ll work directly with the client’s team as a dedicated engineer throughout the project. If you have experience building production financial infrastructure and care about the security of digital asset operations, this is your place.\nTech environment: MPC / custodial wallet platforms (Fireblocks, DFNS or similar), API integrations, stablecoins, DeFi (vaults), Web3\nAs a Senior Blockchain Engineer, you will be responsible for:\nHelping scope a pilot that may initially include manual steps, and designing a path toward automation\n\nBuilding solutions on top of an MPC custody platform: lender and borrower accounts, collections wallets, transfers, and sweeps\n\nDefining transaction policies and pre-execution checks, including tight controls on permitted destinations\n\nIntegrating outputs from an external calculation agent, or from internal calculations, without making smart contracts the primary money movement layer\n\nDesigning and implementing automated wallet operations (deposit flows, sweeps, transfers) with a strong focus on security and auditability\n\nCollaborating with the client’s team, product, and business stakeholders to build solutions that fit real needs\n\nTaking shared ownership of the system from design through deployment and ongoing support\n\nWhat we expect from you:\nHands-on experience building secure money movement solutions on MPC or custodial infrastructure (e.g. Fireblocks, Fordefi), primarily via API\n\nExperience with signing policies, transaction authorization, and wallet controls\n\nExperience with transaction automation and exchange-style flows: deposit and sweep flows\n\nKnowledge of DeFi sufficient to design integrations with confidence (deep smart contract expertise is not required)\n\nExperience building production financial infrastructure that critical business processes depend on\n\nStrong software engineering fundamentals: you write clean, testable code and think about maintainability and security\n\nThe judgement to navigate trade-offs between security, speed of delivery, automation, and cost, and to communicate those decisions clearly to technical and non-technical stakeholders\n\nEnglish proficiency at C1 level or above (for international client collaboration)\n\nPolish language skills at B2 level or above (for smooth communication with the team)\n\nGreat if you also bring:\nFamiliarity with credit facility models, stablecoins, and vault integrations\n\nExperience designing custody architecture and permission models (roles, limits, whitelisting, multi-approval)\n\nExperience with security infrastructure: key management, auditing, transaction monitoring\n\nSmart contract development experience (Solidity) as an additional asset\n\nWhat helps us stay balanced:\nGrow your skills and hobbies with us - make use of a dedicated training and wellbeing budget\n\nWork from home or the office - your choice, up to 100% remote\n\nAccess to specialists whenever you need them via our LuxMed healthcare package\n\nIf the gym is your second home, activate a Multisport card with us\n\nLooking for a long-term home? You're in the right place - stable collaboration, no dress code, no heavy atmosphere\n\nOur team knows how to have fun: board games, city outings, go-kart races, laser tag, great food on team retreats - we take integration seriously (in the best way :)\n\nTech stack\nBlockchain","description_format":"text","description_chars":3715,"description_truncated":false,"requirements":{"experience_years_min":null,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[]},"benefits":[],"hiring_locations":[{"name":"Poland","iso":"PL","kind":"country"}],"hiring_excludes":[],"relocation_offered":false,"industries":["Blockchain & Crypto","Cryptocurrencies","Custom Software Development"],"lifecycle":[{"event":"open","at":"2026-11-05T14:26:00Z"}],"visa":[],"liveness":{"score":90,"band":"hot","label":"Hiring now","p_open":1,"p_active":0.903,"p_room":1,"age_days":2,"expected_fill_days":35,"reasons":["seen:2","velocity","win:early"],"computed_at":"2026-11-08T05:47:12Z"},"pay":{"stated_usd_annual":98100,"is_top_pay":false},"html_url":"https://alion.io/job/4soft-senior-blockchain-engineer","json_url":"https://alion.io/job/4soft-senior-blockchain-engineer.json","meta":{"generated_at":"2026-11-08T11:14:01Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","about":"Alion is a live layer of people, companies and AI agents: who they are, whether they are real and active right now, what they do and how to work with them, readable by people and by agents and paid per call.","catalog":"https://alion.io/catalog.json","usage":{"tier":"crawler_verified","counted_by":"address","units_charged":1,"used_today":24144,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-11-09T00:00:00Z"}},"offers":[{"id":"company.slices","title":"One company in depth, by slice","status":"live","price":{"credits":0.02,"usd":0.002,"plus_per_slice":{"credits":0.05,"usd":0.005}},"unit":"per company, plus each slice with data","note":"the employer in depth","call":{"mcp_tool":"get_company","arguments":{"id":4465305},"rest":"https://alion.io/mcp/rest/get_company?id=4465305"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2F4soft-senior-blockchain-engineer"},{"id":"market.stats","title":"A market slice: pay, demand and time to fill","status":"live","price":{"credits":1,"usd":0.1},"unit":"per slice","note":"pay, demand and time to fill for this role and place","call":{"mcp_tool":"market_stats"},"human":"https://alion.io/catalog?offer=market.stats&for=job%2F4soft-senior-blockchain-engineer"},{"id":"job.search","title":"Open jobs by role, technology, place, pay and visa","status":"live","price":{"credits":0.02,"usd":0.002},"unit":"per posting in a list","note":"similar open postings","call":{"mcp_tool":"search_jobs"},"human":"https://alion.io/catalog?offer=job.search&for=job%2F4soft-senior-blockchain-engineer"},{"id":"company.verify","title":"Is this company real and active right now","status":"pilot","price":null,"unit":"per company","request":{"url":"https://alion.io/catalog/request","method":"POST","body":"{\"offer\": \"company.verify\", \"for\": \"job/4soft-senior-blockchain-engineer\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2F4soft-senior-blockchain-engineer"}],"agent":{"mcp":"https://alion.io/mcp/jobs","mcp_open":"https://alion.io/mcp/open","next":[{"tool":"get_job","arguments":{"id":3809934}},{"tool":"search_jobs","arguments":{"company":"4soft.co","detail":"compact"}},{"tool":"match_people","arguments":{"job_id":3809934},"note":"people open to offers who fit this vacancy"}],"note":"The same data through MCP tools: https://alion.io/mcp/open needs no sign-in (compact searches, postings, people); https://alion.io/mcp with an Alion account has everything. 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