Summary: Sponsored gas is now production-grade across ERC-4337, EIP-7702 “smart EOAs,” and L2s with native AA—letting you remove the “buy ETH first” step, batch flows, and pay with USDC, all while preserving procurement-grade controls. This guide shows exactly how to implement it, what to avoid post‑Pectra, and how 7Block Labs ships measurable ROI with a pragmatic, security‑first stack.

Title: How to Integrate “Sponsored Gas” for Frictionless User Onboarding

Hook: The technical headache nobody budgets for Your conversion dies on the first click. Users hit “Swap,” then the wallet asks for ETH they don’t have, or to approve 3 separate calls. Engineering hacks together a faucet, support tickets climb, and procurement asks why infra spend is growing while activation stalls. Meanwhile, product just needs “one‑tap, no‑ETH onboarding” that Finance can reconcile.

Since May 7, 2025, Ethereum mainnet supports EIP‑7702 via the Pectra upgrade—letting EOAs temporarily act like smart accounts for batching and sponsorship. In parallel, ERC‑4337 paymasters are standard across Base/OP chains and beyond, and L2s like zkSync/Starknet ship native paymaster flows. You no longer need to choose between UX and control—you can have both if you wire the stack correctly. (blog.ethereum.org)

Agitate: What it costs to get this wrong

• Missed deadlines: 4337 mempool quirks, EntryPoint version drift, or an over‑permissive paymaster can stall mainnet launch by weeks. ERC‑7562 rules now gate what bundlers accept; violate them and your UserOps don’t land. (docs.erc4337.io)
• Fraud and user loss: Post‑Pectra, “one‑sign” 7702 delegations created real phishing losses when wallets authorized malicious delegates; mishandled revocation worsens impact. (panewslab.com)
• Vendor lock‑in: Private paymaster APIs without ERC‑7677 mean rewrites when you change providers or chains. (eips.ethereum.org)
• OPEX surprises: Token‑gas paymasters like Circle charge end users a 10% gas markup (waived until June 30, 2025; then live)—great UX, but Finance needs a cost envelope and receipts. (circle.com)

Who this is for (and the keywords you care about)

• Head of Product, Consumer Fintech on Base/OP Stack: “DAU‑to‑Activation,” “first onchain action,” “per‑DAU COGS,” “A/B activation,” “onramp conversion,” “chargeback exposure,” “batching approvals,” “USDC‑only gas.”
• Director of Engineering, Wallets/Infra: “EntryPoint v0.8/v0.9,” “ERC‑7677 paymasterService,” “ERC‑7562 compliance,” “paymaster stake/deposit,” “EIP‑7702 undelegation,” “passkeys (P‑256/WebAuthn),” “ERC‑7579 modular accounts,” “pm_getPaymasterData / StubData.”
• Procurement / Risk: “SLA/SLO with bundler failover,” “cap table of staked entities,” “SAST/bytecode audit evidence,” “rate limits & allowlists,” “observable sponsorship policy,” “data minimization (PII‑free).”

Solve: 7Block Labs methodology for Sponsored Gas that survives audits We ship a dual‑path AA stack that balances UX, control, and portability:

1. Gas policy blueprint (business logic first)

• Choose who pays and with what:
  • “Free gas” for first session: verifying paymaster that sponsors only allowlisted methods/params and per‑user quotas.
  • “Token‑gas” for power users: ERC‑20 paymaster (e.g., USDC) with real‑time FX and daily caps; Circle Paymaster if you want turnkey USDC sponsorship across chains that support it. (docs.erc4337.io)
• Define sponsorship triggers you can defend to Finance:
  • Onboarding events (KYC pass‑through, first swap ≤ $25)
  • Recovery flows (paymaster covers guardian add/remove)
  • Promotions (weekly 3 gasless actions)
• Codify an “observability contract”: per‑UserOp cost, sponsor, policyId, and reconciliation tags into your data lake.

1. Architecture decisions that avoid lock‑in

• Default path: ERC‑4337 v0.8/0.9 with ERC‑7677 paymaster web services (pm_getPaymasterStubData/pm_getPaymasterData) for deterministic, wallet‑discoverable sponsorship UX. Use viem’s paymaster helpers to standardize integration. (github.com)
• 7702 path for atomic UX: Use EIP‑7702 to keep the user’s familiar address and batch critical flows; implement a safe “undelegation” path and recognize wallet restrictions (e.g., MM limiting arbitrary delegates). (alchemy.com)
• L2‑native AA where it shines: On zkSync Era and Starknet, use native paymasters to cut overhead and simplify token‑gas. (docs.zksync.io)
• Modular accounts via ERC‑7579 to avoid wallet‑specific plugins; carry your modules (validators/executors/hooks) across Safe, Kernel, Biconomy. (erc7579.com)

1. Security‑first paymaster design (passes red‑team and procurement)

• Enforce ERC‑7562: deterministic validation, bounded gas, isolated state; stake any entity that needs external reads; reputation‑aware throttling to stay in the shared mempool. (docs.erc4337.io)
• “Verifying paymaster” pattern: off‑chain policy service signs UserOps; on‑chain paymaster verifies signature and deposit coverage; restrict bundlers and allowlists. Coinbase’s reference VerifyingPaymaster is a good baseline. (github.com)
• 7702 guardrails: trusted delegation targets only; explicit undelegation playbook; simulate effects; detect wallet UIs that block arbitrary 7702 signing and provide fallbacks. (alchemy.com)
• EntryPoint hygiene: upgrade to v0.8 or v0.9 to get native 7702 support and paymaster signature decoupling; fix old “initCode”/postOp accounting footguns. (github.com)

1. Infra you control, with vendor escape hatches

• Bundlers: multi‑region, multi‑vendor with OP Stack conditional RPC support; health probes on inclusion rate, time‑to‑inclusion, and throttling signals. (docs.optimism.io)
• Paymasters: run your own plus integrate ERC‑7677‑compliant providers (Base Paymaster, Coinbase CDP Paymaster) behind policy proxies; toggle sponsorship per campaign. (docs.base.org)
• Libraries: permissionless.js + viem for typed AA flows and quick paymaster swaps. (github.com)

1. Implementation playbook (with exact calls)

A) ERC‑4337 + ERC‑7677 (Base, OP chains, Ethereum)

• Wallet discovers capabilities, then calls the paymaster service:
  • get stub data for estimation → finalize paymaster data → sign → send UserOperation.
• TypeScript (viem + permissionless.js) minimal example:

import { createSmartAccountClient } from 'permissionless';
import { createPaymasterClient } from 'viem/account-abstraction';
import { http } from 'viem';

// 1) Create a paymaster client that speaks ERC‑7677
const paymaster = createPaymasterClient({
  transport: http(process.env.PAYMASTER_URL!) // ERC‑7677 endpoint (pm_getPaymasterData/StubData)
});

// 2) Smart account client (bundler URL can be vendor or self‑hosted)
const client = createSmartAccountClient({
  account, // your 4337 account instance
  chain,   // e.g., base
  bundlerTransport: http(process.env.BUNDLER_URL!),
  paymaster
});

// 3) Build + send a sponsored UserOp
const hash = await client.sendUserOperation({
  uo: { target, data, value: 0n, /* ... */ },
  paymaster: { policyId: 'onboarding-v1' } // provider-specific context
});

• Base “paymasterService” capability (ERC‑7677) and gasless guides are now first‑class in Base docs; sponsorship limits and credits are configurable via CDP. (docs.base.org)

B) EIP‑7702 “smart EOA” path (batching + sponsorship without new address)

• Use your existing signer address, and—if needed—delegate to a trusted smart account implementation; wallets may restrict arbitrary delegates.
• Alchemy’s 7702 guidance covers delegation + undelegation flows and known wallet constraints:

Key operational note: to undelegate, sign an authorization delegating to address(0) and submit a direct L1/L2 tx (bundlers won’t relay undelegations). (alchemy.com)

C) zkSync Era native paymaster (token‑gas with EraVM)

• SDK exposes

  paymasterParams

  in tx custom data with “ApprovalBased” or “General” flows; Era has a testnet paymaster for quick starts. (docs.zksync.io)

const tx = {
  to: RECEIVER,
  value: 1n,
  customData: {
    paymasterParams: getPaymasterParams(PAYMASTER_ADDR, {
      type: 'ApprovalBased',
      token: USDC_ADDR,
      minimalAllowance: 1n,
      innerInput: new Uint8Array(),
    }),
  },
};
await wallet.signAndSend(tx);

D) Starknet paymaster (native AA, SNIP‑29/9 compat)

• starknet.js now exposes Paymaster flows including fully “sponsored” transactions; ensure SNIP‑9‑compatible accounts. (starknetjs.com)

import { PaymasterRpc } from 'starknet';
const paymaster = new PaymasterRpc({ default: true }); // or pass a specific service URL
await account.execute(calls, { paymaster });

E) USDC‑only gas with Circle Paymaster (ERC‑4337 v0.7/v0.8, 7702‑compatible)

• Zero developer fee; end user pays a 10% gas uplift where applicable; supports EOAs via 7702 and SCAs via 4337 on multiple chains (Arbitrum, Base, etc.). Great for “USDC‑native” fintech UX. (developers.circle.com)

Best emerging practices (Q1–Q2 2026)

• Adopt ERC‑7677 now so wallets can natively discover/route to your paymaster; it also makes switching providers trivial. (eips.ethereum.org)
• Enforce ERC‑7562 locally: throttle/bounce userops that violate validation scope; publish stake/deposit dashboards per paymaster to keep inclusion rates high. (ercs.ethereum.org)
• Standardize on EntryPoint v0.8+; v0.9 adds paymasterSignature for parallel signing, better error messages, and events for 7702. Plan deprecation of legacy v0.6/v0.7 internally. (github.com)
• Prefer ERC‑7579 modular accounts to avoid SDK‑specific plugins; reuse validators (passkeys), hooks (session keys), and executors across stacks. (erc7579.com)
• On Base/OP Stack, use the conditional RPC/mempool features tuned for 4337 bundlers to reduce reorg pain and inclusion variance. (docs.optimism.io)

Proof: GTM metrics and how to measure ROI (what we report to Product, Finance, and Procurement) Your CFO doesn’t care about “4337 vs 7702”—they care about CAC payback and COGS. Here’s how we quantify impact:

• Activation lift: % of new wallets who complete a first onchain action within 24 hours.
  • Sponsored gas typically cuts the “fetch ETH” drop‑off and consolidates approvals into a single action. Base’s own docs emphasize sub‑penny fees, which—paired with sponsorship—remove the biggest UX cliff on day 0. (docs.cdp.coinbase.com)
• Cost per activated user: (sponsored gas spend + paymaster markup + infra) / activated users.
  • If your median sponsored action on Base is $0.003 and you sponsor 3 actions, your per‑user gas COGS baseline is under one cent; with USDC paymaster at +10% uplift, it’s still cents‑scale, not dollars. (docs.cdp.coinbase.com)
• Reliability SLOs: time‑to‑inclusion p95, inclusion rate, and userops rejected for ERC‑7562 violations. OP Labs’ BigQuery 4337 datasets and the ERC‑4337 metrics guide let us compute daily paymaster volumes and inclusion by chain/app. We wire these to a dashboard your ops team can own. (docs.erc4337.io)
• Fraud/safety: % of 7702 delegations to non‑allowlisted targets; undelegation MTTR; number of rejected phishing‑pattern requests flagged by simulations per 1k sessions. Wallet/provider docs explicitly call out 7702 constraints and undelegation procedures—our runbooks follow them. (alchemy.com)
• Procurement controls: per‑policy spend caps, rate limits, geo/state rules, and signed receipts (policyId, paymaster, userOpHash) exported for Finance.

What we implement in 2–6 weeks (example milestones) Week 1

• Architecture choice doc: 4337+ERC‑7677 primary, 7702 fallback; L2 coverage. Policy design with Finance (caps/allowlists/receipts).
• Pick providers per chain: e.g., Base Paymaster + self‑hosted verifying paymaster; Pimlico/Alchemy bundlers; Circle Paymaster for USDC flows. (docs.base.org)

Week 2–3

• Integrate viem/permissionless.js; add wallet capability checks; wire pm_getPaymasterStubData/Data; add Policy Service with signed sponsorships and contract/method allowlists. (eips.ethereum.org)
• EntryPoint v0.8+ deployment checks; stake/deposit sizing; ERC‑7562 sim harness in CI. (github.com)

Week 4

• zkSync/Starknet paymaster pilot on a narrow flow (e.g., USDC tip or swap) with native AA for lower overhead. (docs.zksync.io)
• 7702 batch‑only path for high‑value flows; implement undelegation UI + docs.

Week 5–6

• A/B experiment: gasless vs control in top 2 flows; measure activation lift, p95 inclusion, per‑DAU COGS; hand off dashboard + runbooks (reconciliation, alerts, abuse).

Practical snippets you can paste this sprint

1. ERC‑7677: get stub for estimation, then finalize data

// Estimation phase (stub)
const stub = await paymasterClient.getPaymasterStubData({
  sender, nonce, callData, maxFeePerGas, maxPriorityFeePerGas, /* ... */
  context: { policyId: 'onboarding-v1' } // provider-defined
});

// After gas calc, request final data
const final = await paymasterClient.getPaymasterData({
  sender, nonce, callData, /* ... */, context: { policyId: 'onboarding-v1' }
});

// Merge into UserOp and sign

Spec methods are standardized; viem wraps both calls for you. (eips.ethereum.org)

1. EntryPoint v0.9 parallel paymaster signature (cut UI latency)

• v0.9 adds a dedicated paymasterSignature field so users don’t wait for provider signing before the wallet confirmation appears; reduce drop‑offs on slow networks. (github.com)

1. 7702 undelegation runbook (paste into your wiki)

• Fund the account with native gas.
• Sign EIP‑7702 authorization delegating to address(0) with currentNonce+1.
• Submit an empty tx with the authorization (bundlers don’t relay undelegations). (alchemy.com)

1. zkSync “ApprovalBased” paymaster (USDC token‑gas)

• Use EraVM‑compiled contracts; testnet has a built‑in paymaster to speed pilots. (docs.zksync.io)

Risk controls we bake in (so Security says “yes”)

• Strict allowlists (contract+selector+arg bounds) and rate limits per user/session; no blanket sponsorship.
• Staked entities with reputation budgets; ban on shared mutable state in validation unless staked, per ERC‑7562. (ercs.ethereum.org)
• Phishing‑aware 7702: only delegate to audited implementations; simulate effects; surface human‑readable summaries; one‑click undelegation.
• Evidence for Procurement: EntryPoint version, paymaster code hash, audits, bundler SLOs, and signed sponsorship receipts.

Where we plug into your roadmap (and how we’re accountable)

• If you need fast track to mainnet: we deliver an “MVP sponsored gas” that meets Finance’s reconciliation and Risk’s gating within 4–8 weeks, depending on chain coverage and wallet mix.
• If you want zero‑vendor lock‑in: we ship ERC‑7677 and ERC‑7579‑aligned modules so you can rotate providers without rewriting the app. (eips.ethereum.org)

Services you’ll likely need (and how we can help)

• Strategy and architecture: Map your user journeys to the right AA path (4337/7702/native) and chains. See our custom [blockchain integration services] and [cross‑chain solutions development].
  • Blockchain integration
  • Cross‑chain solutions development
• Delivery: We stand up paymasters, bundlers, and wallet UX using our hardened templates in Foundry/TypeScript and Cairo/EraVM. See our [web3 development services] and [custom blockchain development services].
  • Web3 development services
  • Blockchain development services
• Security: We threat‑model 7702 delegation risks, audit verifying/token paymasters, and add detection rules for ERC‑7562 violations.
  • Security audit services
• Product enablement: We ship dashboards and GTM experiments that show activation lift and per‑DAU gas COGS. For protocol teams, we also support [fundraising] to scale user subsidies responsibly.
  • Fundraising

Appendix: What changed recently (why now)

• Pectra activated May 7, 2025: EIP‑7702 is live—batching, sponsorship, and recovery flows without new addresses. (blog.ethereum.org)
• EntryPoint v0.8: native 7702 support + ERC‑712‑style signatures; v0.9: faster paymaster signature flow and better observability. (github.com)
• Standardization wave: ERC‑7677 (paymaster API), ERC‑7562 (validation rules/reputation), ERC‑7579 (modular accounts) stabilized AA integrations and reduced vendor risk. (eips.ethereum.org)
• Providers matured: Base/CDP Paymaster with credits; Circle Paymaster for USDC; zkSync/Starknet native paymasters; OP Stack enhancements for bundlers. (docs.cdp.coinbase.com)

The decision framework (pick your stack in 60 seconds)

• You want USDC‑only gas and the broadest wallet reach today → ERC‑4337 v0.8/0.9 with ERC‑7677, plus a USDC paymaster (Circle or self‑hosted token paymaster). Add 7702 fallback for atomic flows. (eips.ethereum.org)
• You want zero infra vendors and atomicity → 7702 “smart EOA” with a vetted delegate; sponsor selectively via 4337 when token‑gas is required. (alchemy.com)
• You want the lowest per‑action overhead on a single L2 → zkSync/Starknet native AA paymasters. (docs.zksync.io)

Personalized CTA If you’re the Head of Product at a fintech launching on Base in Q2 2026 and you need “day‑0 activation without ETH,” book our 45‑minute Gasless Readiness Review: we’ll simulate your top five flows on Base, size per‑DAU COGS, define an ERC‑7677 policy that Finance can approve, and deliver a one‑sprint implementation plan. Start here with our [web3 development services] or speak directly to our AA architects via our [blockchain development services] page.

• Web3 development services
• Blockchain development services