# Explore Ethereum-like blockchain privately with your RPC URL

Source: https://github.com/paulmillr/esplr

## Summary

esplr is a browser-based explorer for Ethereum-like blockchains that sends requests only to a user-specified RPC URL, avoiding third-party block explorers that log address lookups. It shows ETH and token balances and transaction history, converts balances to USD using on-chain Chainlink contract prices, and integrates with Sourcify for smart contract source verification. The project's README says it supports ERC-20 token transfer history, with a first query taking up to 50 seconds and later queries cached, while ERC-721 NFT support is still in progress. It recommends a self-hosted Erigon 3 archive node for full functionality, since some third-party providers have rate limits that make transaction history unavailable.

## Article

esprl

Explore Ethereum-like blockchain privately with your RPC URL.

Important

The package got merged into micro-eth-signer. Check out its examples directory.

🔒 No 3rd party services: only private RPC requests

💹 ETH and token balances, transaction history

💵 On-chain USD price conversion from oracles

📜 Integration with Sourcify for smart contract source code verification

🪶 100KB gzipped. 3 files: 1 html, 1 css, 1 js

Motivation

How is this better than Etherscan?

Etherscan and other other 3rd party block explorers collect and track user data. They create logs every time someone opens an address. Private explorers allow viewing information without logging.

How is this better than Otterscan?

Otterscan does not support token balances or transfer history, which makes it limited in usefulness. ERC20 / ERC721 / ERC1155 tokens & NFTs are one of the most popular features of EVM-like blockchains. Besides that, Otterscan can only be used with one client while esplr strives to support all node types.

Can I verify all network requests?

The explorer only makes requests to specified RPC URL. To audit this, check src/App.vue, handleConnect. It uses micro-ftch to ensure no requests are done outside of the URL. You can add custom logging there.

How are USD prices calculated?

Chainlink EVM contract provides onchain prices. No external services are used.

Are ERC-20 tokens fully supported?

Yes. To view full token transfer history for an account, open tx Details tab. First call can take up to 50 seconds because of limitations of ETH nodes. Second call would be cached and instant.

Are ERC-721 NFTs fully supported?

Work in progress. They will be shown in UI in one of the next updates.

Do you support local or remote Sourcify integration?

Both! Check out instructions below to set up your own Sourcify instance.

Which frontend libraries are used?

micro-eth-signer and micro-ftch empower data retrieval. Vue.js is used as UI framework.

Setup

To build the app and launch dev server, execute:

npm install && npm run dev

To build for production:

npm install && npm run build # Output is now in `dist/` # Example: serve `dist/` directory using built-in Python module cd dist && python3 -m http.server --bind 127.0.0.1

The output is 3 files in dist: 1 html, 1 js, 1 css.

Docker image

Continuously re-generated via GitHub Actions and published to Docker registry.

See relevant Docker image URL.

Optional: RPC and Sourcify configuration

You can have the app automatically point to an RPC URL, SOURCIFY URL or IPFS GATEWAY URL provided via env variables: VITE_RPC_URL, VITE_SOURCIFY_URL, VITE_IPFS_GATEWAY_URL.

For example:

npm install && VITE_RPC_URL=<RPC_URL> VITE_SOURCIFY_URL=<SOURCIFY_URL> VITE_IPFS_GATEWAY_URL=<IPFS_GATEWAY_URL> npm run dev

Running RPC backend

Esplr supports all node types. User-ran Erigon RPC node is adviced to get 100% of functionality. Reth may achieve feature parity soon. See details.

Download Erigon and start it:

erigon --datadir=/data/erigon --prune.mode='archive' --torrent.download.rate="100mb" --http --http.api=eth,erigon,web3,net,debug,trace,txpool,ots --ws --http.corsdomain='*'

Initial sync will take 8 hours for ETH mainnet on 100Mbps connection (slower ones can still be used). After that RPC will be running on port 8545.

The RPC will be running locally at 127.0.0.1:8545. There are two ways to make it available to outside internet:

Redirect e.g. ethnode.com to 127.0.0.1:8545

Can be achieved with NGINX: proxy_pass http://127.0.0.1:8545

You will probably need domain and SSL certificate. For example, if domain is ethnode.com, you will be able to specify its RPC.

It is suggested to use basic auth (user:password@ethnode.com).

Or, use SSH tunneling to forward port 8545 to your local machine: ssh -L 5678:127.0.0.1:8545 root@192.168.1.50 where 5678 is port on your local machine, root@192.168.1.50 is user + hostname of Erigon3 server.

Reth, Geth, Nethermind, Infura

Some features are not present outside of Erigon. The app uses archive node API / trace_filter extensively.

Self-hosted Erigon 3 works with prune.mode=archive for 100% of features

3rd-party (infura / alchemy / quicknode) Erigon nodes have strict rate limits: tx history is not available

Reth nodes do not have tx history because of lack of indexes. They indicated willingness to fix the issue

Geth, Nethermind do not have proper low-resource archive mode, so they are not supported for querying tx history

Sourcify

esplr supports Sourcify (sourcify.dev) integration. Sourcify allows to verify smart contract source code for eth. To set it up:

Download manifest.json

curl -L -O https://repo-backup.sourcify.dev/manifest.json

Download all files from manifest.json

To fetch chain-specific archives for eth mainnet (chain id 1):

CHAIN_ID=1; jq -r '.files[].path' manifest.json | grep -E "(full|partial)_match\.${CHAIN_ID}\." | xargs -I {} curl -L -O https://repo-backup.sourcify.dev/{}

Alternatively, there is 260GB+ archive for all chains:

jq -r '.files[].path' manifest.json | xargs -I {} curl -L -O https://repo-backup.sourcify.dev/{}

Extract files from archives:

for file in *.tar.gz; do echo "Extracting $file..."; tar -xf "$file"; done

Normalize names of addresses directories:

Copy script

cp scripts/normalize_addresses.sh /path/to/repository

Chain-specific normalization (takes 2+ hours):

./normalize_addresses.sh --chains 1

Normalization of all chains (takes 24+ hours):

./normalize_addresses.sh

Run any static file server with CORS enabled on the repository dir:

npm install -g http-server@14.1.1

http-server /path/to/repository --cors -p 2015

In esplr settings, specify address and port of the static file server

Speed

Most requests are instant. Some requests, like seeing token transfer history, rely on scanning whole blockchain from scratch. This can take 10-50 seconds.

To improve this, in the future, archive node developers can add additional indexes into their software. They can also provide a new RPC method to query history. Best thing one can do is to ask for this in their bug trackers: reth, erigon.

Addons, like Trueblocks, can also speed things up. While the goal of esplr is to use "pure" archive node, we would welcome support for an easy trueblocks integration.

Hardware requirements

An archive node will need 30Mbps connection & 2.5TB NVME SSD (TLC, not QLC). Such new PC can cost $570 for 32GB RAM & 4-core CPU. Here is another $650 build with 64GB RAM & 8-core CPU.

Similar server can be rented from providers like Hetzner for $60/mo. Make sure to prohibit private IPs in firewall.

Fully validating non-archive node can have <1TB storage requirements. Check out Ress and EIP-7870.

License

MIT License

## Comments

**mishaderidder.eth**: > Releasing ESPLR - a local ETH block explorer.

> Big problem of ecosystem is reliance on 3rd party RPCs (infura, alchemy, quicknode). Also reliance on 3rd party explorers (etherscan). They track users: it makes system one big panopticon.

> Local nodes can make the situation better!

> PC with an archive node only costs $40/mo or $500 one-time. Esplr only needs RPC URL of an archive node. It can view transactions, account balances and token transfer history (unique feature).

https://warpcast.com/paulm/0x7dc9fa37