How to Build a Multi-Institution Bitcoin Custody Platform: A Step-by-Step Guide

Introduction

Bitcoin custody traditionally forced institutions to choose between convenience and security: centralized platforms carried counterparty risk, while self-custody demanded technical expertise and operational overhead. Onramp, an Austin-based bitcoin financial services firm, has pioneered a middle path with its Multi-Institution Custody (MIC) model. By distributing key control across several regulated custodians, MIC removes single points of failure while keeping assets verifiable on-chain. This guide walks you through the exact steps Onramp took—from conceptualizing the model to scaling it with a $12.5 million Series A round—so your organization can implement a similar framework.

How to Build a Multi-Institution Bitcoin Custody Platform: A Step-by-Step Guide — Source: bitcoinmagazine.com

What You Need

Institutional commitment to bitcoin as a reserve asset or treasury tool
Partnership agreements with at least two regulated custodians (e.g., BitGo, Coincover, Tetra Trust)
Key sharding technology to split private keys into fragments distributed across custodians
Compliance and legal review for multi-jurisdictional key storage
Platform development resources (or white-label solutions) for brokerage, cash management, and reporting
Capital allocation for product development and commercial expansion
Strategic advisors with traditional finance experience (e.g., former Blackstone partner David Thayer)

Step 1: Identify the Custody Tradeoff and Define a Solution

Begin by analyzing the two extremes in digital asset safekeeping: single-entity custodians (e.g., exchanges) that create counterparty risk, and self-custody that burdens clients with key management. Onramp recognized that neither option scales for institutions needing compliance, auditability, and ease of use. Their solution: a multi-institution model where key control is shared, not delegated solely to one party. Document the specific pain points your institution faces and map them to a distributed control architecture.

Step 2: Design a Multi-Institution Key Distribution Framework

The core of MIC is breaking a single bitcoin private key into multiple fragments—using technologies like Shamir’s Secret Sharing or threshold signatures—and distributing those fragments to independent, regulated custodians. Each custodian holds a piece that alone cannot move funds. Onramp’s system requires thresholds (e.g., 2 of 3 or 3 of 5) for signing transactions. Design your own threshold scheme based on security needs and jurisdictional requirements. Ensure that no single custodian can unilaterally authorize a withdrawal.

Step 3: Partner with Trusted Custodial Firms

Onramp selected BitGo, Coincover, and Tetra Trust as its initial custodial partners. Each brings regulatory licensing, insurance coverage, and operational reliability. When choosing partners, evaluate their compliance track record, custody infrastructure (cold storage, multi-sig support), and willingness to participate in shared key control. Sign legal agreements that define liability, key storage procedures, and recovery protocols. Consider spreading custodians across different jurisdictions to mitigate regulatory and geopolitical risks.

Step 4: Build a Full Financial Services Platform

Custody alone is insufficient for institutional adoption. Onramp launched Onramp Finance in April to combine bitcoin custody with brokerage (licensed in all 50 U.S. states), cash accounts with rewards, a payments card, bitcoin IRAs, and even gold access within a single interface. Develop or integrate similar services to create a “full bitcoin financial stack.” Prioritize features that reduce friction for institutional clients, such as automated reporting, API integrations, and treasury management tools.

Step 5: Secure Early Institutional Clients

Onramp’s first high-profile client was UK pension fund Cartwright, which selected Onramp as custodian for its bitcoin allocation. The Bitcoin Policy Institute also endorsed multi-party custody for potential state-level bitcoin reserves. Target similar institutional partners that value regulatory compliance and auditability. Offer pilot programs, white-glove onboarding, and proof-of-reserve attestations to build trust. Highlight zero security incidents since 2023 as a differentiator.

Step 6: Raise Capital to Scale

With $1 billion in assets under custody and clear market traction, Onramp raised $12.5 million in Series A funding led by Early Riders, valuing the company at $135 million. Use the capital in two parallel tracks: product development (platform improvements and licensing custody infrastructure to other custodians) and commercial expansion (sales team growth, white-label offerings for banks and fintechs). Appoint strategic advisors like former Blackstone partner David Thayer to bridge traditional finance and crypto expertise.

Tips for Success

Never compromise on security. Onramp’s zero-incident record is a direct result of distributing key control. Regularly audit your key distribution and custody partners.
Prioritize regulatory alignment. Work with custodians that are regulated in multiple jurisdictions. This will ease future licensing and institutional adoption.
Think beyond custody. Institutions want a single provider for custody, brokerage, lending, and cash management. Build an integrated stack or partner with white-label solution providers.
Leverage proof-of-reserve. On-chain verifiability of assets boosts client confidence. Make it a core feature of your reporting.
Target niche adopters first. Pension funds, policy institutes, and state treasuries are early adopters for multi-institution custody. Tailor your messaging to their risk appetite and compliance needs.
Prepare for white-label licensing. Onramp plans to license its custody infrastructure to other regulated custodians. This creates a recurring revenue stream and scales the model without direct client acquisition costs.

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