Block explorer

How to run the public block explorer at https://explorer.coincync.network. Lives in /deploy/explorer/.

Architecture (one-line)

A single Caddy reverse proxy on port 443, fronting a localhost-bound coincync-node jsonrpsee server, with the embedded block explorer HTML served from GET / and POST /api/{testnet,mainnet} proxying to the cyncd RPC.

The explorer UI loads chain data only through that JSON-RPC surface (same-origin /api/testnet or /api/mainnet). On the Blocks page it walks the full canonical height range using batched get_block_range (100 heights per request, server-capped) so the table can list every block the upstream node stores, without thousands of per-height round trips.

Recent UX hardening keeps the CoinCync visual style while making chain views more operator-friendly:

• blocks/mempool/network/health/iron pages show explicit source + freshness badges,
• the blocks table supports newest reset + height jump + progressive backfill,
• duplicate low-signal widgets were removed from high-traffic pages to prioritize chain state.

    public 443/tcp ── Caddy ── 127.0.0.1:28081 (cyncd testnet RPC)
                        │   └─ 127.0.0.1:19081 (cyncd mainnet RPC, post-launch)
                        ├─── /var/www/explorer/index.html (embedded HTML)
                        └─── /static/vendor/* (vendored CDN assets)

Files

First-time deploy

On the explorer host (currently LON):

# 1. Pre-flight: confirm cyncd is bound to localhost only
ss -tlnp | grep -E ':(28081|19081) '
# Expect: 127.0.0.1:28081 (testnet RPC). Mainnet RPC appears post-launch.
# DO NOT see 0.0.0.0 — that defeats the entire Caddy security model.

# 2. Pre-flight: confirm 80/443 are clear and DNS resolves
ss -tlnp | grep -E ':(80|443) '   # expect nothing
dig +short explorer.coincync.network
# Expect: the IP of the current explorer host (see operator inventory)

# 3. Open public ports in DigitalOcean firewall: 80/tcp and 443/tcp.
#    DO NOT also open 28081 (the whole point is that only Caddy is public).

# 4. Pull and deploy
cd /opt/coincync
git pull --ff-only
cd deploy/explorer

# 4a. (Recommended) vendor the CDN dependencies
./fetch-vendor.sh
# Reviews + commits checksums.txt
git add static/vendor && git commit -m "explorer: vendor CDN deps"

# Then patch index.html to use the vendored paths
./patch-vendor.sh
git add ../../src/explorer/index.html && git commit -m "explorer: use vendored assets"

# Re-run lib tests to confirm the CDN-enumeration test still passes
cargo test --lib -p coincync explorer

# 4b. Start Caddy
docker compose up -d
docker compose logs -f caddy   # watch the ACME handshake

First request to https://explorer.coincync.network/ triggers Let’s Encrypt cert provisioning (~5 seconds). Subsequent requests are instant.

Verification

curl -I https://explorer.coincync.network/
# expect: HTTP/2 200, content-type: text/html, cache-control: public, max-age=300, must-revalidate

curl -sX POST https://explorer.coincync.network/api/testnet \
     -H 'content-type: application/json' \
     -d '{"jsonrpc":"2.0","id":1,"method":"get_info"}' | jq .

# Mainnet pre-launch returns 502 (no upstream). Post-launch returns chain data.
curl -sX POST https://explorer.coincync.network/api/mainnet \
     -H 'content-type: application/json' \
     -d '{"jsonrpc":"2.0","id":1,"method":"get_info"}' -w '\n%{http_code}\n'

Updating the explorer HTML

The HTML is bind-mounted live from src/explorer/index.html. To update:

cd /opt/coincync
git pull --ff-only       # pulls any changes to src/explorer/index.html
# Caddy doesn't need to restart. The HTML cache is 5 minutes, so worldwide
# rollout completes in ≤ 5 minutes.

To force-refresh immediately, docker compose restart caddy.

Production keep/remove checklist

Use this as the default trim for the public explorer. The goal is a safer, lower-noise operator surface.

Keep (public-by-default)

• home (summary, latest blocks, chain status)
• blocks, block, tx, mempool (core explorer flow)
• network, health (operational observability)
• supply, burn (tokenomics transparency)
• privacy, about, constitution, changelog (project/legal context)
• docs, api, search, faucet (user support and read-only API docs)

Dev-only or remove from public nav

• wallet (browser key generation risk, even with warnings)
• apilive (encourages ad-hoc probing from browsers)
• txbuilder (implies browser tx construction workflow)
• multisig (advanced flow better documented in wallet/CLI docs)
• balancelookup, richlist (privacy/targeting metadata amplification)
• webhooks, livestream (non-essential attack surface and data churn)
• status, miningtutorial, governance (better hosted in docs pages, not top nav)

Runtime control now in index.html

The explorer now defaults to production mode, which hides the dev-only pages above.

• Public deployment behavior: pages are hidden and direct navigation falls back to home
• Local dev override: run on localhost or 127.0.0.1 with ?dev_explorer=1
• External dependency override: remote assets/fetches are disabled by default and only enabled on localhost with ?allow_external_deps=1

Example:

http://localhost:19082/?dev_explorer=1

Security model

The explorer host is a trust boundary. Every public-facing HTTP request lands on Caddy, which enforces:

• TLS via Let’s Encrypt (auto-provisioned, auto-renewed)
• HSTS preload (Strict-Transport-Security: max-age=31536000; includeSubDomains; preload)
• CSP (default-src 'self' target posture; temporary external origins must stay explicitly documented and minimized)
• Rate limit of 60 req/min per source IP (whose primary purpose is making industrial-rate scraping by chain-forensics firms expensive — see Federation & DDoS)
• Body size cap of 64 KB per request (mirrors the rest.rs proxy’s cap)
• Method allowlist enforced by the upstream rest.rs proxy when the explorer’s JS calls /api/v1/...
• No third-party MITM (no Cloudflare, no CDN, no edge cache that sees decrypted traffic)

The cyncd node itself is NOT exposed publicly. Caddy proxies allowlisted requests to it on localhost. Any attacker who finds a vulnerability in jsonrpsee can still only hit it through Caddy’s allowlisted method set, with the rate limit applied.

What this stack deliberately does NOT do

• Cloudflare in front — see Federation & DDoS. The whole reason to NOT use a CDN is structural to the privacy-coin threat model.
• Per-user authentication — every endpoint is read-only and rate-limited. Authentication on a write-capable wallet endpoint lands in P1.
• Transaction submission — submit_block and send_raw_transaction are blocked from the public REST proxy by RPC_ALLOWED_METHODS. Wallets that need to submit transactions submit to their own local node, not to the public explorer.
• Tx-by-hash lookup — get_transaction returns a labelled NotImplemented because the chain doesn’t yet have a txid → (block_height, tx_index) index. Lands in P1.
• Asset queries — permanently NotImplemented. CoinCync 1.0 stripped the confidential-asset layer.

Adding a .onion mirror

See Tor hidden services. The same Caddy stack can additionally serve the explorer over an .onion for users whose threat model demands strong anonymity. ~20 minutes of setup, additive to the clearnet site.

See also

• Federation & DDoS — why this is one host and not behind a CDN
• Public RPC API — the parallel deployment for the API subdomain
• Tor hidden services — adding .onion availability
• The deploy/explorer/README.md source file — has the same content as this page plus operator-runbook details