Why Data Availability Dictates User Fees

The gold standard for DA, where security is priced into every byte. Using Ethereum's calldata or blobs is a direct pass-through of its high security and decentralization costs.

• Cost Driver: ~$0.10 - $1.00+ per 100KB blob, fluctuating with base fee.
• Trade-off: You pay for ~$100B+ in staked economic security, making it non-negotiable for high-value chains.
• For: Sovereign chains and L2s where security is the product.

Decouples execution from consensus and DA, selling pure bandwidth at commodity prices. Its cost advantage is its core value proposition.

• Cost Driver: ~$0.0001 per 100KB, orders of magnitude cheaper than Ethereum.
• Trade-off: Relies on a smaller, dedicated validator set (~$1B+ staked), a calculated security trade-off.
• For: Cost-sensitive rollups (e.g., many Alt-L1 rollup kits) and high-throughput appchains.

Hybrid approaches that use cryptoeconomic security (restaking) or optimized validator networks to undercut Ethereum while claiming enhanced security over pure modular DA.

• EigenDA: Leverages Ethereum's restaking pool (~$20B TVL) for security, targeting near-Ethereum security at lower cost.
• Avail: Uses a dedicated PoS network with validity proofs, focusing on high throughput for sovereign chains and rollups.
• For: Rollups seeking a middle ground on the security-cost spectrum.

For any rollup, DA is not an optional feature—it's the single largest recurring infrastructure cost after sequencer profits. Choosing wrong strangles scalability.

• Fee Composition: In an Optimistic Rollup, ~80-90% of the L2 fee can be the cost to post data to L1.
• Scalability Ceiling: Throughput is capped by the cost and bandwidth of the underlying DA layer.
• Result: User experience (low fees) is directly gated by your DA procurement strategy.

The emerging market treats DA as a wholesale commodity, where rollups can auction their data needs or use multiple providers for different data types.

• Mechanism: Platforms like EigenDA and Celestia allow rollups to bid for block space, creating a competitive fee market.
• Innovation: NearDA and similar solutions offer ultra-cheap archival storage, separating urgent availability from long-term storage.
• Future: Modular stacks let you mix-and-match DA based on transaction criticality (e.g., high-value DeFi on Ethereum, social feeds on Celestia).

The 'best' DA layer is determined by your rollup's specific security budget and throughput requirements. The market is a live auction for security.

• High-Value Chains (DeFi, Bridges): Must pay the Ethereum premium. It's insurance.
• High-Volume Chains (Gaming, Social): Will commoditize to Celestia or Avail. Cost is king.
• Hybrid Chains: Will use restaked networks like EigenDA for a balanced profile.
• Bottom Line: User fees are the clearest signal of which auction you're in.

Using Ethereum for data availability is secure but creates a fee floor for all L2s. Every byte of calldata competes for the same scarce block space, making cheap micro-transactions impossible.

• Cost Driver: ~80% of an L2's operational cost is DA fees paid to Ethereum.
• Scalability Cap: Throughput is limited by Ethereum's ~80 KB/s data bandwidth.
• Result: User fees are a direct tax on Ethereum's consensus premium.

Separate data publishing from consensus to create a competitive marketplace for block space. This decouples L2 security costs from Ethereum's monolithic fee market.

• Cost Reduction: DA costs drop by 10-100x versus Ethereum calldata.
• Throughput: Dedicated DA chains offer 1-100 MB/s of data bandwidth.
• Trade-off: You exchange Ethereum's maximal security for economic security and faster finality.

Your DA layer defines your fee structure's asymptotic limit. Ethereum provides a high, inelastic cost floor. Modular DA offers a low, elastic one, enabling new use cases.

• For DeFi Primitives: Ethereum DA's security may justify its cost.
• For Mass Adoption (Social, Gaming): Modular DA's sub-cent fees are non-negotiable.
• Key Metric: The cost per byte of your DA layer is your protocol's most important economic parameter.

Even with EIP-4844 blobs, all L2s share a global resource pool. A surge on Arbitrum or Optimism can spike fees for every chain using Ethereum for DA, creating correlated fee volatility.

• Problem: No isolation between L2 economies; they compete for the same blob space.
• Solution: Dedicated DA layers (Celestia) or reserved bandwidth (EigenDA) provide fee isolation.
• Result: Predictable fee curves are a feature of the DA layer, not the execution client.