If you ship a wallet, a portfolio dashboard, or a contract-monitoring service, the block explorer API you pick decides three things: how many chains you can cover with one auth flow, how much you pay at scale, and how easy it is to migrate when a chain goes out of fashion. This guide compares the four explorer APIs developers actually evaluate in 2026 — Etherscan API V2, Blockscout, Routescan, and Helius — plus the RPC-plus-indexer pattern from Alchemy and QuickNode that increasingly replaces them.
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A block explorer API exposes the same data you see in a browser: transactions, internal transactions, token balances, event logs, contract source code, and holder lists. It indexes onchain state into queryable endpoints so an app can fetch one address's full history in a single HTTPS call rather than scanning every block over RPC.
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The classic Etherscan-style request looks like this:
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The response is a JSON envelope: status ("1" on success), message, and result (an array of transaction objects with blockNumber, timeStamp, hash, from, to, value, gasUsed, isError, and roughly fifteen other fields). Blockscout mirrors this envelope on its ?module=account&action=txlist path for drop-in compatibility, which is the single most useful design choice in the explorer-API world.
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Etherscan API V2 is the default pick for EVM coverage. The 2024 V2 release consolidated the legacy per-chain endpoints (etherscan.io, bscscan.com, polygonscan.com, arbiscan.io, optimistic.etherscan.io, snowscan.xyz, basescan.org, and others) into a single base URL with a chainid parameter, so one API key works across every supported network.
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According to the Etherscan API documentation, the free tier covers most read-heavy use cases. The free plan publishes a 5 calls/second ceiling on the public endpoint, which is the figure Etherscan documents on its API plans page. Paid tiers (Standard, Advanced, Professional) raise per-second throughput and unlock Pro endpoints like daily token-transfer aggregates, gas oracle history, and holders-list pagination beyond the free cutoff. Pricing and exact rate limits change; treat the docs at docs.etherscan.io as the source of truth before you commit a budget.
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Strengths: ubiquity, contract-verification endpoints (getsourcecode), and the largest set of third-party tutorials on the internet. Weaknesses: closed-source data pipeline, no archive-trace endpoints on the free tier, and you cannot self-host.
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Blockscout is the open-source explorer that ships as the default on most rollup launches — Optimism, Gnosis Chain, Filecoin's FVM, Rootstock, and dozens of L2 testnets all run Blockscout instances. Each instance exposes two APIs: a legacy Etherscan-compatible API (same module/action shape as the example above) and a REST API V2 with cleaner resource paths like /api/v2/addresses/{hash}/transactions.
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The Etherscan-compatibility layer is the migration story: an app written against Etherscan can repoint its base URL to a Blockscout instance and keep working for the most common account, contract, and token actions. Blockscout's documentation at docs.blockscout.com lists the supported endpoints and the small handful that diverge.
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Hosted Blockscout instances are typically free up to a per-IP soft limit; if you need guaranteed throughput, you self-host the Elixir backend against your own archive node. That removes the rate-limit ceiling entirely, but you take on operational cost: an EVM mainnet archive plus the Blockscout indexer is rarely cheaper than a paid Etherscan plan unless you're issuing hundreds of millions of calls.
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Routescan is the explorer behind snowtrace.io (Avalanche C-Chain), the official Avalanche subnet explorers, and a long tail of EVM L2s and appchains. Its API at routescan.io exposes both an Etherscan-compatible legacy module and a REST surface, with one request shape that switches networks via a path parameter rather than a query parameter.
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Where Routescan wins is coverage of chains the bigger players ignore: Avalanche subnets, Beam, Dexalot, DOS Chain, and the various Layer-3 rollups that ship a Routescan instance on launch day. If your wallet has to support a long tail of EVM networks beyond Etherscan's V2 list, Routescan is usually the second key you add. Free-tier limits and paid pricing are documented on the Routescan developer portal; verify before integrating because the published tiers have shifted between 2024 and 2026.
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Solana doesn't have an Etherscan-style explorer API as a category leader. The closest equivalent is Helius, which packages a Solana RPC node with an enhanced indexer that returns parsed transactions, parsed token balances, NFT metadata, and webhooks for address activity. Solscan and SolanaFM publish public APIs as well, but Helius is the developer-facing default because of its parsed-transaction endpoint, which decodes Anchor instructions into human-readable JSON.
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Helius prices on a credits model rather than calls-per-second: each plan grants a monthly credit budget, and different endpoints consume different credit weights (an enhanced parsed-transaction call costs more than a raw getAccountInfo). The free Developer plan documents a generous monthly credit allowance suitable for prototyping; production wallets typically land on the Business or Professional tiers. Pricing pages on helius.dev change frequently — pull current numbers before you forecast costs.
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One caveat worth flagging: every "free tier" number above can change without notice. Pull the current docs page before you write a forecast. The numbers Etherscan, Blockscout, Routescan, and Helius publish on their own sites are the only ones to trust.
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For a wallet that needs to show transaction history across the major EVM chains plus Solana, the cleanest 2026 stack is Etherscan API V2 for EVM coverage, Helius for Solana, and a Blockscout fallback for any rollup that isn't on Etherscan's V2 list yet. That's two paid keys plus one open-source instance, and it covers roughly 95% of the chains a consumer wallet sees in practice.
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If you also need archive-trace data (internal transactions for older blocks, debug traces, full receipts), the explorer-API tier alone won't be enough. Layer in an Alchemy or QuickNode RPC subscription for trace and debug methods, and keep the explorer APIs for indexed reads like address transaction lists and token balances. This split is what most production wallet teams converge on.
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Different products lean on different parts of the explorer surface area. Picking the right primary API depends on the read pattern that dominates your traffic, not the chain count on a marketing page.

The Etherscan-compatible module/action shape is the closest thing to a portable interface across explorers. If you write your client to that shape and keep base URLs configurable, you can fail over from Etherscan to a Blockscout instance for a given chain in production without code changes. Most teams that have run wallets through one explorer outage learn this the hard way; it's worth designing the abstraction in on day one.
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For payment-flow reads specifically — checking that a user-funded address received a stablecoin payment — the explorer API is rarely the right primary. Confirmations ship faster from a direct RPC subscription. Use the explorer for backfills and historical lookups, and lean on RPC for the live path. Eco exposes a routes API that abstracts this distinction for stablecoin transfers across chains so apps don't reimplement the explorer-plus-RPC dance per network.
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Comparison drawn from official documentation pages for each provider as of May 2026: docs.etherscan.io (V2 endpoints, plans page), docs.blockscout.com (Etherscan-compatible API, REST V2), routescan.io developer portal, and docs.helius.dev (credits model, enhanced endpoints). RPC-plus-indexer notes reference public Alchemy and QuickNode product pages. Free-tier rate limits and pricing change frequently; always verify on the vendor docs page before committing infrastructure budget.
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