Code

Code is a mobile payments application built on Solana by Ted Livingston, the founder of Kik Messenger. Designed to recreate the simplicity of physical cash in digital form, Code lets users send money anywhere in the world using QR codes — no fees charged to the recipient, no phone number or email address required, and no public record of individual balances or transaction histories. Originally built around the Kin SPL token, Code evolved into a new product called Flipcash in June 2025, swapping Kin for USDC-backed stablecoins and deepening its partnership with Coinbase.

Core Mechanism

The central technical innovation beneath Code is the Code Sequencer, a layer-2 system built on top of Solana mainnet. Solana's roughly 400ms average block time creates unpredictability for real-time payment flows — transactions can fail to land in blocks without a mempool, making on-the-spot commerce feel unreliable. The Code Sequencer addresses this by maintaining a global state and running local simulations of submitted transaction intents before submitting and scheduling them on Solana. Because it schedules cryptographically signed transactions without ever holding user funds or private keys, the sequencer is both permissionless and self-custodial.

Payments flow through four stages: local simulation, transaction submission, scheduling, and on-chain confirmation. This architecture allows the app to guarantee an instant experience at the point of interaction even when Solana is under congestion, with permanent settlement following once the network recovers. A purpose-built Code VM, also deployed on Solana, further reduces on-chain fees for high-frequency micropayment traffic.

Features

Code's user-facing design centres on three payment primitives. The primary method is a QR-code scan: one user generates a digital bill and another scans it in person to claim the funds. The second is image sharing — the same QR bill can be sent as an image through WhatsApp, iMessage, or any messaging app, allowing remote transfers without the recipient sharing any contact details. The third is CashLinks, URL-based payment claims that can be embedded anywhere on the web or dropped into a chat.

Across all three methods, the core properties remain constant: transactions confirm in under a second from the user's perspective, fiat-denominated amounts are supported in over 100 currencies with automatic conversion at the edges of the network, and wallet balances are not publicly visible on-chain.

Developer SDK

Code shipped an open SDK that lets any web developer embed a Pay with Code button accepting micropayments as small as 5 cents, with a flat 1-cent fee covering all blockchain costs. The SDK covers JavaScript and TypeScript client libraries alongside server-side packages for Node, Python, PHP, and Go, with ready-made examples for React, Vue, and plain HTML. It supports tipping, login-gated content paywall patterns, and idempotency keys that prevent duplicate charges. A gRPC-based API sits beneath the SDK for advanced integrations, including payment status polling, lifecycle hooks, and server-side webhook verification — the recommended approach over browser events, which can be intercepted on mobile.

Tokens

Code was originally built around Kin, an SPL token on Solana with roots in Kik Messenger's 2017 initial coin offering, which raised roughly $100 million. In Code's original architecture, users deposited in their local fiat currency, which converted to Kin for settlement across the Code Sequencer, then converted back to fiat on the receiving end. Kin's price volatility was a persistent friction point for a payments product targeting everyday use.

In June 2025, the team dropped Kin entirely when launching Flipcash. The new product settles in USDC and in USDF, a USDC-backed stablecoin issued by Coinbase through its Custom Stablecoin service. Flipcash was reportedly the first application to use Coinbase's stablecoin-as-a-service platform. The shift eliminated volatility risk and aligned the product with Solana's growing stablecoin infrastructure.

Security

Code's three Solana programs — Timelock, Splitter, and Swap-validator — are open-source and audited by OtterSec. The Timelock program implements state-channel mechanics: funds are locked in timelocked accounts with a 21-day fallback unlock period, ensuring users can always reclaim funds independently even if the Code Sequencer becomes unavailable. The Splitter program provides the on-chain privacy layer, mixing transaction outputs so individual balances remain opaque.

A Rendezvous Key mechanism establishes a trusted communication channel between the mobile client and the sequencer for each payment intent. The key is derived from a SHA256 hash of a 20-byte payload and is used to sign all messages related to a given intent. Critically, the sequencer receives only the public portion of this key — it can route messages but cannot modify payment details, preventing a compromised sequencer from altering amounts or destinations.

In November 2023, the team open-sourced the iOS and Android apps, all server infrastructure, and supporting libraries under the MIT license.

Team

Code was founded by Ted Livingston, who previously built Kik Messenger — one of the first mobile chat apps to reach 100 million users and the first chat app available on BlackBerry. Livingston and the same core team of nine people transitioned from Kik through the Kin token project to Code over approximately a decade, giving the group unusual continuity for a crypto startup.

In February 2024, Code raised a $6.5 million seed round led by M13 and Union Square Ventures. The angel cohort included Balaji Srinivasan, Roham Gharegozlou (Dapper Labs founder), and Solana co-founders Anatoly Yakovenko and Raj Gokal. Yakovenko publicly stated Code's UX set the standard for consumer payments apps. Participation from both Solana co-founders at the seed stage underscored the team's position within the Solana ecosystem.

Solana Fit

Code's architecture reflects a deliberate bet on Solana as the only public blockchain where sub-cent consumer payment fees are achievable at scale. Solana's throughput and low base fees handle the settlement layer, while the Code Sequencer and Code VM handle the UX guarantees that raw L1 interactions cannot reliably provide.

Kin migrated from an Ethereum-adjacent chain to Solana in 2020, and all subsequent Code infrastructure was built natively on Solana programs using the Anchor framework. The June 2025 pivot to Flipcash retained Solana as the settlement layer while adopting USDC and Coinbase's USDF as the unit of account, aligning the product with Solana's expanding real-world payments and stablecoin ecosystem.

Current Status

By mid-2025, Code as a standalone branded product had been superseded by Flipcash. The getcode.com domain changed hands, the @getcode Twitter account went dormant, and the Code app's Kin-based payment rails were retired. The code-payments GitHub organization remained active, with Flipcash's server infrastructure, iOS app, and Android app built on the same open-source foundations Code established. The Code SDK documentation remained available at code-payments.github.io for developers who had integrated micropayments using the original SDK.