Summary: Post-Pectra, Ethereum gives you three viable account abstraction paths: ERC‑4337 with paymasters and bundlers, pure bundler flows without sponsorship, or “native” approaches via EIP‑7702 on L1 and RIP‑7560-style native AA on L2s. This guide compares costs, risks, UX, and integration details—down to gas constants, addresses, and pricing—so you can choose the right AA stack for your product.

Paymasters, Bundlers, or Native? Choosing Your Post‑Pectra AA Stack

Decision point: after Ethereum’s Pectra upgrade went live on May 7, 2025, you now have credible options to ship modern wallet UX without forcing users to hold ETH. But each path—ERC‑4337 (bundlers/paymasters), bundler-only 4337, or native (EIP‑7702 on L1 and native AA on L2s)—comes with different trade‑offs across cost, operational complexity, censorship resistance, and time‑to‑market. Below is a practical, implementation‑level guide from 7Block Labs on how to decide and deploy. (ethereum.org)

What Pectra actually changed for AA (and why it matters to your stack)

• EIP‑7702 (Set EOA account code) lets an EOA temporarily delegate execution to smart‑contract code within a single transaction, enabling batching and third‑party sponsorship patterns in the canonical mempool. Key constants: transaction type 0x04; PER_AUTH_BASE_COST = 12,500 gas per authorization tuple; PER_EMPTY_ACCOUNT_COST = 25,000. Practically, this makes “programmable” EOAs possible without a 4337 stack for some use cases. (eips.ethereum.org)
• EIP‑7623 (Increase calldata cost) raises the floor cost for calldata‑heavy transactions, which affects userOp payloads in 4337 more than minimal 7702 flows. Expect pressure to keep userOps lean. (eips.ethereum.org)
• EIP‑7691 (Blob throughput increase) doubles target blobspace (3→6 blobs) and raises the max (6→9), lowering L2 DA costs and improving economics for AA-heavy L2 apps. (eips.ethereum.org)

Together, these mean: 4337 remains feature‑rich but has payload overhead; 7702 unlocks canonical‑mempool UX improvements on L1; L2s keep getting cheaper and more “native” for AA. (docs.erc4337.io)

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Your three post‑Pectra choices

1) 4337 with paymasters and bundlers (full stack)

Best when you need token‑gas payments, sponsored onboarding at scale, or modular smart‑account features (session keys, spending limits, recovery) across many chains.

What you use:

• EntryPoint: v0.6 address 0x5FF1…2789 (widely deployed) and v0.7 address 0x0000000071727De22E5E9d8BAf0edAc6f37da032 (newer, more efficient). Align account code with the correct

  validateUserOp

  signature (v0.6 uses

  UserOperation

  , v0.7 uses

  PackedUserOperation

  ). Plan migration to v0.7 before 2026 deprecation of v0.6 by some providers. (alchemy.com)
• Bundlers: Pimlico, Alchemy, Infura/MetaMask, Thirdweb. Example pricing signals: Pimlico PAYG ~ $0.0075/userOp unsponsored (and 10% surcharge on mainnet verifying/erc20 paymaster coverage); Alchemy Gas Manager charges 8% admin fee on sponsored gas plus bundler API compute costs ($0.001575 per userOp with typical endpoints). (docs.pimlico.io)
• Paymasters: verifying paymasters for gasless flows; ERC‑20 paymasters for stablecoin gas (USDC common). Providers include Pimlico (singleton paymaster), Biconomy (SDK V4), and Circle Paymaster (USDC, 10% end‑user fee starting July 1, 2025; previously waived). (github.com)
• Standards: ERC‑7562 validation‑scope rules (required for safe simulation), ERC‑7677 (wallet–paymaster web‑service capability), and modular account standards ERC‑6900/7579 if you need plugin ecosystems. (ercs.ethereum.org)

Operational realities:

• Gas overhead: ERC‑4337’s indirection adds ~42k gas vs native. Keep userOps small to limit EIP‑7623 impact. (docs.erc4337.io)
• Mempool: fragmentation has improved with the live Shared Mempool (peer‑to‑peer gossip of userOps) on Ethereum, Arbitrum, and Optimism, boosting inclusion guarantees and resilience. (docs.erc4337.io)

When to pick this:

• You want cross‑chain, token‑gas onboarding now (e.g., USDC everywhere), strong module ecosystems, and you can accept extra infra moving parts. (docs.erc4337.io)

2) 4337 without paymasters (bundlers only)

You still get smart‑account UX (batching, session keys, recovery) while users pay native gas. This reduces operational exposure (no paymaster funding/surcharges), keeps compatibility with EntryPoint v0.7, and benefits from the Shared Mempool. It’s a good middle ground for teams that want 4337 UX but not gas sponsorship. (github.com)

3) “Native” approaches

• L1: EIP‑7702. Your app (or a sponsor) sends a standard transaction carrying authorization tuples; the EOA temporarily delegates to your wallet logic contract. This uses the canonical mempool—no bundlers—and supports batching and sponsorship patterns where Account X pays on behalf of Y by submitting the 7702 tx. Remember 7702 is not a paymaster: you either have the sponsor submit the tx (paying gas) or the user pays ETH; there’s no built‑in token‑gas on L1 without 4337. Key constants and semantics are in the spec; design to the

  0xef0100 || address

  delegation indicator rules. (eips.ethereum.org)
• L2: Native AA (RIP‑7560‑style). Several rollups have native AA designs (e.g., Starknet; zkSync’s AA is 4337‑like but protocol‑native). Native AA integrates validation into the protocol with canonical mempools and simpler inclusion guarantees, and targets lower overhead than 4337. Expect L2s to standardize on RIP‑7560 variants first. (starknet.io)

When to pick this:

• You want fewer moving parts (no bundler/paymaster), can live without token‑gas (on L1), and prefer canonical‑mempool guarantees. On L2, you want the most “built‑in” UX and cost efficiency possible. (eips.ethereum.org)

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Concrete selection criteria (with numbers and non‑obvious gotchas)

• Need token‑gas on Ethereum L1?
  • Choose 4337 + ERC‑20 paymaster (e.g., USDC). 7702 alone can’t do token‑gas; it can do sponsorship (X pays gas for Y) by submitting the transaction, but not “pay gas in USDC” from Y. Budget for paymaster surcharges (e.g., 8–10%) and plan finance workflows. (alchemy.com)
• Calldata sensitivity after EIP‑7623:
  • If your flows pack large userOps (signatures, modules), 4337 costs rise more than 7702 because 7702 tx payloads can be slimmer. Prioritize v0.7 accounts and compressed encodings; avoid bloated

    paymasterAndData

    . (eips.ethereum.org)
• Inclusion guarantees:
  • 7702 and native AA use canonical mempools; 4337 relies on an alt mempool that is now “shared,” improving but not identical to canonical guarantees. If you need the strongest L1 inclusion semantics without extra infra, bias toward 7702 for eligible flows. (docs.erc4337.io)
• Ecosystem lock‑in vs modularity:
  • 4337 + ERC‑6900/7579 unlocks module portability across accounts and vendors; this matters for long‑lived apps and security reviews. Native 7702 is more bespoke: you own the wallet logic contract and must maintain it like any protocol surface. (eips.ethereum.org)

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Implementation patterns we recommend in 2025

Pattern A: L1 consumer app with no‑ETH onboarding and stablecoin gas

• Stack: 4337 (EntryPoint v0.7) + verifying paymaster + ERC‑20 paymaster (USDC) + Shared Mempool bundlers (Pimlico/Alchemy/Infura).
• Why: Immediate token‑gas on mainnet, maximum wallet compatibility, and SDK maturity.
• Details to get right:
  • Use EntryPoint v0.7 (address 0x0000000071727De22E5E9d8BAf0edAc6f37da032) if your smart account supports

    PackedUserOperation

    . This yields better gas estimation and structured errors. (alchemy.com)
  • Keep userOps small to mitigate EIP‑7623: tighten signature encodings; avoid “fat”

    context

    bytes from paymasters; pre‑install modules rather than configuring them per‑op. (eips.ethereum.org)
  • Budget for fees: e.g., Alchemy ~8% admin on sponsored gas + small per‑userOp API compute; Pimlico ~10% paymaster surcharge on mainnets; Circle Paymaster charges end users 10% of gas from July 1, 2025 (previously waived). (alchemy.com)
  • Enforce ERC‑7562 rules; stake paymaster and factory contracts so bundlers don’t throttle your ops. (ercs.ethereum.org)

Pattern B: L1 pro‑trader UX without 4337 infra

• Stack: EIP‑7702 only.
• Why: You want canonical‑mempool inclusion, atomic batched actions (approve + swap), or privileged sub‑keys for bots with no 4337 infra.
• How:
  • Sponsor‑pays: your service submits the 7702 transaction with the user’s authorization tuple(s) and pays gas; you monetize fees off‑chain or by programmatic settlement. Gas constants: 0x04 tx type; 12,500 gas per authorization tuple; consider

    COLD_ACCOUNT_READ_COST=2600

    on delegated resolution. (eips.ethereum.org)
  • Batch DEX flows: a single 7702 tx can run “approve if needed → swap” atomically using your delegated wallet logic.
  • Guardrails: adopt internal nonce and spending limits in the delegated code; clear delegation between actions per the spec’s “delegation designation” behavior. (eips.ethereum.org)

Pattern C: Gaming or social on L2 with built‑in AA

• Stack: Native AA on Starknet or zkSync; optional 4337 compatibility layers only where needed.
• Why: Lowest per‑action overhead, canonical mempool, and wallet UX (session keys, spending caps) by default.
• How:
  • Starknet: every account is a contract; leverage session keys and spending limits via account contract logic. (starknet.io)
  • zkSync Era: use its native AA and paymasters; its design is 4337‑like but protocol‑embedded—read system contract patterns like

    NonceHolder

    and

    ContractDeployer

    . (docs.zksync.io)
  • Roadmap: watch RIP‑7560 (native AA tx type) convergence—expect more L2s to adopt variants that reduce 4337’s ~42k gas overhead. (docs.erc4337.io)

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Best emerging practices (you can implement this quarter)

• Dual‑path SDK: ship both 4337 and 7702 clients. Default to 4337 for token‑gas; fall back to 7702 for ETH‑paying power users or when bundlers misbehave. This gives you canonical‑mempool escape hatches when needed. (eips.ethereum.org)
• Move to EntryPoint v0.7 where possible; plan for v0.6 EOL by some providers in 2026. Validate your account’s first parameter type to confirm compatibility. (alchemy.com)
• Adopt ERC‑7677 now: it standardizes how wallets talk to your paymaster web service (pm_getPaymasterStubData, pm_getPaymasterData), reducing vendor coupling and enabling wallet‑driven sponsorship UX. (eips.ethereum.org)
• Respect ERC‑7562: keep validation deterministic and resource‑bounded; stake any entity (paymaster, factory, aggregator) that needs external reads during validation; otherwise bundlers will throttle you. (ercs.ethereum.org)
• Size matters post‑EIP‑7623: cap

  context

  sizes, prefer aggregators for compact signatures, and aggressively strip optional metadata from userOps. This directly lowers fees. (eips.ethereum.org)
• Consider modular account standards for longevity: ERC‑6900/7579 let you swap validators/executors and reuse audited modules across providers (ZeroDev Kernel, Biconomy, OKX, Safe ecosystems). (eips.ethereum.org)

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A crisp decision framework (5 minutes to alignment)

• You need token‑gas L1 today, or multi‑chain onboarding with mature tooling and analytics.
  • Choose: 4337 + paymaster + Shared Mempool bundlers. Budget 8–10% admin on sponsored gas + per‑userOp infra. (alchemy.com)
• You need canonical‑mempool inclusion and can fund gas either from the app (sponsor) or user’s ETH.
  • Choose: EIP‑7702. Use it for atomic, batched UX and delegated execution without extra infra. (eips.ethereum.org)
• You target L2 and want the least overhead and simplest path to at‑scale UX.
  • Choose: the L2’s native AA (Starknet, zkSync), and align with RIP‑7560’s direction. Optional 4337 compatibility only for wallet reach. (starknet.io)

Hybrid is often best: many production apps run 4337 + paymasters for onboarding and keep a 7702 path for power users or incident response, plus native AA on their “home” L2.

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In‑depth example: USDC‑gas checkout on L1 + 7702 fallback

• Primary: 4337 with USDC paymaster (Circle/Pimlico/Biconomy).
  • Flow: wallet constructs userOp → wallet requests paymaster stub/data (ERC‑7677) → bundler simulates (ERC‑7562) → handleOps → paymaster covers gas in USDC with admin fee (8–10% typical). (eips.ethereum.org)
• Fallback: 7702 batched tx for users holding ETH.
  • Flow: user signs 7702 authorization; your app submits a single canonical tx that performs approve+swap+pay, no bundler. Gas constants per‑auth: 12,500; ensure your delegated code clears or updates delegation as needed. (eips.ethereum.org)
• Why this works: you maximize conversion (no‑ETH onboarding) and avoid outages if a paymaster policy throttles or a bundler degrades—users with ETH can still complete via 7702.

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Security and compliance checklists

• 4337 stacks:
  • Stake paymasters and factories; implement reputation/ban logic awareness to avoid throttling (per ERC‑7562). Log and alert on

    FailedOp

    events. (ercs.ethereum.org)
  • Version‑pin EntryPoint (v0.7 preferred) and monitor address usage across chains (0x…032 for v0.7, 0x…2789 for v0.6). (alchemy.com)
• 7702:
  • Treat the delegated wallet logic like production protocol code: audits, upgradability strategy, and explicit limits (e.g., per‑tx and per‑day caps) to prevent privilege escalation via sub‑keys. Align with EIP‑7702’s rules on code‑loading and EXTCODE* behavior during delegation. (eips.ethereum.org)
• L2 native:
  • Follow chain‑specific account standards and system‑contract patterns (e.g., zkSync

    NonceHolder

    , Starknet SNIP‑6). Confirm canonical mempool rules for inclusion. (docs.zksync.io)

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Timelines and budgets we see in 2025

• 4337 “MVP” with sponsored gas and swaps: 4–8 weeks to production for a senior team using Pimlico/Alchemy + Biconomy SDK; infra OPEX includes paymaster admin fees (8–10%), bundler API usage, and your settlement/reconciliation. (docs.pimlico.io)
• 7702 “batch‑only” UX: 2–4 weeks if you already have audited execution logic; OPEX mainly on gas and monitoring, not infra vendors. (eips.ethereum.org)
• L2 native AA: varies—Starknet/zkSync teams ship in 3–6 weeks if familiar with their SDKs; lowest per‑action costs, best for high‑frequency apps. (starknet.io)

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The 7Block Labs recommendation by product type

• Fintech/Payments at scale (global): 4337 with USDC paymaster + ERC‑7677 integration; add 7702 fallback. Plan gradual v0.7 migration and keep userOps lean post‑EIP‑7623. (eips.ethereum.org)
• Consumer social/games (frequency > UX): build on an L2 with native AA; add a thin 4337 compatibility layer for wallet reach if required. (starknet.io)
• Trading/DeFi power users: 7702 for canonical‑mempool speed and atomicity; consider 4337 modules for recovery/session keys if your audience needs them. (eips.ethereum.org)

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Final takeaway

Pectra didn’t “kill” 4337; it widened your option set. If you want token‑gas and mature tooling today, pick 4337 (with the Shared Mempool, v0.7, and ERC‑7677). If you want canonical‑mempool atomic UX with minimal infra, 7702 is ready. If you’re L2‑first, native AA beats both on overhead and inclusion. Most successful teams in 2025 run a hybrid.

If you’d like a focused architecture review for your use case, 7Block Labs will map your transactions, signature flows, and cost envelope to the right AA stack in under two weeks.

References: EIP‑7600/Pectra contents and activation; EIP‑7702 spec and constants; EIP‑7623; EIP‑7691; ERC‑4337 core/bundler/paymaster docs; Shared Mempool status; EntryPoint addresses and v0.7 guidance; ERC‑7562; ERC‑7677; Starknet and zkSync native AA docs; RIP‑7560 overview. (eips.ethereum.org)