DEX Migration to StarkNet: From Cairo Contract Development to Verification

Deploying StarkNet smart contracts: where DEXs break

Deploying StarkNet smart contracts rarely breaks at the compilation stage — Cairo contracts compile into bytecode, pass local tests, and the team considers the task closed.

Problems begin later: the contract class is not verified in the explorer because the hash of the compiled artifact does not match the deployed one, and without contract verification, users and aggregators cannot see the source code and do not trust the pool.

The second point of failure is AMM logic during DEX migration.

Moving the math from the EVM model to Cairo breaks the calculations where everything used to add up: rounding during division, the order of fixed-point operations, working with felt types instead of the usual integers.

Externally the contract works, but an audit reveals holes in the pool invariants — and the exchange launch is pushed back while the logic is rewritten.

The third is transactions that "hang." The deployment goes out to the network but does not finalize: the gas limit for Cairo computations is set incorrectly, the sequencer queue is not taken into account, retries for PENDING status are not configured.

As a result, the team wastes time on manual restarts, and some classes remain in an undefined state.

We break down how this is closed: from the structure of Cairo contracts and correct verification to fault-tolerant deployment and DEX migration without downtime.

What Moving a DEX to StarkNet Delivers: Speed and Cost

Moving a DEX to an L2 solution changes three measurable characteristics of an exchange: throughput, gas cost, and transaction finality time.

Instead of competing for space in a block on the mainnet, orders and swaps are executed off it, and only the state confirmation goes to the first layer.

For an exchange, this means that peak load — a surge in trading during volatility — no longer causes some trades to get stuck in a queue.

StarkNet builds proofs of computational correctness rather than recomputing every operation on all nodes. As a result, gas cost drops by an order of magnitude: a transaction that on the mainnet ate up a noticeable share of the trade amount costs fractions of a cent here.

For a market maker this is fundamental — a strategy where every order cancellation cost as much as a separate operation becomes profitable, and liquidity in the order book stays denser.

What Changes in Numbers

• Throughput. The exchange processes many times more operations per unit of time: the bottleneck shifts from the first layer to its own matching services.
• Gas cost. The fee for a swap and an order cancellation drops to a level at which small trades stop being unprofitable.
• Finality. Confirmation arrives in seconds, not minutes — arbitrageurs and bots see the result sooner and don't build their strategy around uncertainty.
• Failure class. The "stuck transaction" goes away: if an operation fails, the state rolls back entirely instead of leaving the user with frozen funds.

A separate benefit is predictability when scaling. As the exchange grows, the load falls on the sequencer and our services, not on the shared blockchain, so the cost of servicing one user doesn't grow linearly with their number.

Migration options: full migration, hybrid, proxy

Migrating a DEX to StarkNet is not "rewrite the contracts and deploy." Cairo differs from Solidity in its computation and state storage model, so the same liquidity pool cannot simply be copied: AMM logic, oracles, and fee calculation are rewritten for the new execution environment.

The choice of scheme determines how long the exchange will live in two networks simultaneously and how liquidity will behave during the transition period.

Full DEX migration is the cleanest path: contracts are written from scratch for Cairo, without legacy compromises, and the architecture is immediately tailored for cheap computation. The cost is the loss of accumulated state and re-launching the pools.

Hybrid migration keeps the working DEX in the source network and raises a mirror in StarkNet, linking them with a bridge.

Liquidity and positions are synchronized, but a delay between networks appears along with the need to monitor price divergence — otherwise arbitrageurs drain the pool.

Proxy contracts provide an immutable address and manageable upgrades, but state still migrates separately: a proxy changes logic, not data. In practice, schemes are combined — a proxy for the entry point, a bridge for liquidity, a redeploy for new pools.

Work stages: from auditing the current DEX to verification

Migrating a DEX to StarkNet is not rewriting contracts "from scratch according to the documentation," but transferring working logic while preserving the behavior of pools, oracles, and swap routing.

That is why we build the process as a sequence with checkpoints: at each one, the client side sees exactly what has been verified and what remains.

1. DEX audit. We analyze the current architecture: how pools are structured, where state is stored, which external calls are critical. We record the invariants — what must be preserved after migration — and the bottlenecks that are more expensive to port than to rewrite.
2. Schema design. We determine the storage layout, the division into modules, and the trust points between them. At this step it becomes clear which parts of the logic go into separate contracts and which remain in one.
3. Writing Cairo contracts. We implement the logic in Cairo, taking into account the computation model and storage costs. We work through error handling and access controls separately — on StarkNet, the cost of an incorrect call is higher than in familiar networks.
4. Environment setup and testnet. We set up a local test bench and run through swap, liquidity addition, and liquidity withdrawal scenarios. The testnet provides validation against real behavior before publication to the mainnet.
5. Contract verification. We publish the sources, compare the bytecode against the compiled artifact, and check build reproducibility. Without this, the contract formally works but is unprovable for users and auditors.
6. Handover. We deliver configurations, deployment schemas, the upgrade policy, and rollback instructions.

Each stage ends with an artifact that can be verified independently of us. Describe your task — we will come back with an estimate and a stage-by-stage plan.

Artifacts: configurations, schemas, access policies, procedures

We hand over the project not as an "archive for memory" but as a working kit that your team or another contractor can use to run contracts without us. Below is what exactly you will have in hand after the deployment of StarkNet smart contracts and acceptance.

• Contract source code — a repository with Cairo contracts, pinned dependencies, and a reproducible build: a single commit produces the same artifact that is deployed on the network.
• Deployment schemas — a map of contracts and their relationships: which contract depends on which, where the proxies and upgrade points are, and in what order components are rolled out when the system is rebuilt.
• Key management policies — who manages which operation, which signatures are required for critical actions, how keys are stored, rotated, and revoked in case of compromise.
• Documentation — a description of public methods and events, an analysis of emergency scenarios, and instructions for local launch and verification of contracts before rollout to the mainnet.
• Upgrade procedures — the process for releasing a new version: preparation, checks, rollout window, conditions for rolling back to the previous version, and the criteria under which an upgrade is halted.
• Verification report — the results of checks and audit with a list of findings and confirmation that the issues are closed in the final build.
• Accesses and roles — a permission matrix for contracts, a registry of addresses, and the procedure for transferring control to your side after handover.

The kit is assembled so that upgrades and rollbacks do not depend on specific people. Describe the task — we will come back with an estimate and a plan for your project.

Case study: DEX migration with 0.3% liquidity loss

Before the migration, the exchange ran on a network with slow confirmation: user transactions got stuck in the queue, swaps depended on an external sequencer, and under peak load some orders never reached execution.

Each such case meant frozen client funds and manual investigation by support. The "stuck transaction" failure class was a standard scenario, not an exception.

What we did

We moved the swap core to StarkNet and rewrote the logic in Cairo — the pool contracts, the router, and the price calculation module. The key decision: we moved order matching into a separate contract so that execution would not be blocked during peaks.

We added a pool state check before every operation — a transaction either goes through entirely or rolls back without loss of funds.

Result

Finality time dropped from minutes to seconds — the user sees swap confirmation almost immediately. Liquidity loss during the pool migration was 0.3%: some providers left at the moment of the pause, but returned within the first day after launch.

Failures of the "stuck transaction" type disappeared completely — not a single case during the observation period.

The exchange's stability no longer depends on an external queue: peak loads are now absorbed at the contract level rather than through manual intervention. Support has been unburdened — there are no more requests about stuck swaps.

How is StarkNet smart contract deployment different from EVM?

The main difference is the execution model. EVM computes every operation on all nodes, so the gas price grows linearly with the complexity of the logic.

StarkNet executes the program off-chain and sends a correctness proof to L1: verification costs roughly the same regardless of how much computation is inside.

For exchange logic, this changes the equation — bulk calculations, order matching, and pool recalculations stop being prohibitively expensive, and the bottleneck becomes not computation but the volume of data that needs to be written to state.

Hence the second difference — gas cost is calculated differently. In EVM you pay for virtual machine steps; in StarkNet — for the so-called step, for the volume of data written, and for storage updates.

A contract that is cheap in EVM in terms of computation but actively writes to storage may turn out to be more expensive than expected in StarkNet.

During DEX migration this is critical: pools, order books, and position accounting need to be designed to minimize writes to state, not just the number of operations.

The third — development tools. The contract language here is not Solidity but Cairo: static typing, explicit memory management, a different type system, and a different approach to storage.

Ready-made EVM standard libraries do not carry over directly — token standards, fixed-point math, and access patterns have to be reimplemented or adapted. Our engineers build this into the architecture from the very start rather than rewriting along the way.

The fourth — verification. In EVM a contract is compiled into bytecode that can be checked against the source. In StarkNet the Cairo compiler produces an intermediate representation, and verifying that the published code matches the source requires a separate process.

For a DEX, where users entrust their funds to the contract, this is not a formality: without correct verification it is impossible to prove that the deployed code is the very one that passed the audit.

That is why verification is included in the migration plan as a separate stage, not as a final touch.

Common technical concerns when migrating a DEX

Migrating a DEX to StarkNet almost always runs into the same engineering questions: how existing wallets will behave, where the risks lie with upgradeable contracts, and how to keep control over keys. Below are the breakdowns that most often come up during the assessment stage, before work begins.

What risks do proxy contracts carry during upgrades?

An upgradeable contract provides flexibility but adds a point of failure: an error in the upgrade logic or loss of admin rights blocks fund withdrawal.

We separate logic and storage, restrict upgrade rights with multisig and a timelock, and cover the upgrade mechanism itself with rollback tests. This way the upgrade remains manageable rather than irreversible.

How is key security and contract auditing ensured?

We store admin and deployer keys in hardware modules and separate them by role — compromising one doesn't grant access to everything. Before launch, the code undergoes internal testing and an external contract audit: we check edge cases, reentrancy, and calculation correctness.

We hand over the audit report and test results to the client along with the deployment configuration.

Let's discuss your DEX migration task on StarkNet

To come back with an estimate and a work plan, we need to understand the current DEX architecture: what stack the contracts are written in, how liquidity pools, oracles, and order routing are structured, and which external services are tied to the smart contracts. Describe this in free form — our engineers will then ask clarifying questions themselves.

The work then proceeds in stages:

• Analysis of the current architecture. We review the contracts, state storage schemas, and dependencies between modules — we record what can be carried over as is and what needs to be rewritten for the StarkNet execution model.
• DEX audit before migration. We check the pool logic, swap calculations, admin rights, and handling of external calls — we find the places that will behave differently on the new network.
• Migration plan and estimate. We break the work into stages: contracts, integrations, testnet, mainnet. For each — scope of work, dependencies, and timelines.
• Development of Cairo contracts. We port the logic taking into account the specifics of the network: separation into components, working with storage, and calls between contracts.
• Testing and verification. We run through swap scenarios, adding and withdrawing liquidity, and check edge cases and failure behavior.
• Deployment and support. We deploy the contracts, verify them in the network explorer, hand over the documentation, and stay in touch after launch.

If the analysis shows that part of the logic is easier to leave on the current network and move only the key operations to StarkNet — we will say so directly. Our goal is to propose a working solution, not the maximum scope of work.

Describe the task — we will come back with a migration estimate, a work plan, and the team composition.