Anatomy of the Transaction Subscriptions endpoint
Creates a subscription that watches a set of wallet addresses and posts a webhook to your callback URL whenever they transact. Manage watched addresses and chains without redeploying, and scale monitoring to large address sets.
curl -X POST "https://api.zerion.io/v1/tx-subscriptions/" \
-H "authorization: Basic <API_KEY>" \
-H "content-type: application/json" \
-d '{
"callback_url": "https://your.app/webhooks/zerion",
"addresses": ["0xabc..."],
"chain_ids": ["ethereum", "base"]
}'{
"data": {
"type": "tx-subscription",
"id": "sub_7f21...",
"attributes": {
"callback_url": "https://your.app/webhooks/zerion",
"wallets_count": 1,
"status": "active"
}
}
}Key parameters
callback_urlbodyHTTPS endpoint that receives a POST when a watched wallet transacts.addressesbodyWallet addresses to monitor within this subscription.chain_idsbodyChains to watch for activity, e.g. ethereum, base.What the Transaction Subscriptions response gives you
One request returns enriched, ready-to-render fields — no decoding, pricing, or post-processing on your side.
Full decoded transaction
Each webhook carries the same rich, decoded tx as the history endpoint.
included[].transactionsSigned & verifiable
RSA-SHA256 signature and a certificate URL to prove authenticity.
X-SignatureSubscription link
Every callback links back to the subscription that fired it.
relationships.subscriptionWatched address
The address that transacted, on the notification payload.
attributes.addressMulti-address
Watch up to 100 addresses per subscription.
addresses[]Chain scope
Subscribe to specific chains or all supported networks.
chain_ids[]Built for production
Everything the Transaction Subscriptions endpoint gives you to ship a real integration — filters, coverage, and predictable limits.
Push, not polling
Create a subscription with a callback URL; Zerion POSTs a decoded transaction the moment a watched wallet moves.
- POST /v1/tx-subscriptions/
- callback_url + addresses (+ optional chain_ids)
- Omit chain_ids to watch every supported chain
Verify every callback
Each webhook is signed so you can confirm it genuinely came from Zerion before acting on it.
- X-Signature — RSA-SHA256
- X-Certificate-URL — public cert to verify against
- Concatenate timestamp + body, then verify
Know the guarantees
Design your handler around real-world delivery semantics.
- Best-effort delivery; retries stop after 3 failures
- Order is not guaranteed
- Prices are null — fetch by hash for value
Dev vs production keys
Test freely on a dev key, then whitelist your callback for production scale.
- Production: up to 100 addresses/sub, no expiry
- Dev: 1 subscription, 5 addresses, 1-week validity
- Whitelist callbacks via [email protected]
What teams build with it
From dashboards to autonomous agents, teams reach for the Transaction Subscriptions endpoint to ship faster.
Real-time alerts
Notify users the instant their wallet sends, receives, or trades — no polling loop.
Automation & agents
Trigger agent workflows or on-chain reactions when a monitored address moves.
Ops & compliance
Watch large address sets for activity and stream events into your pipeline.
Other endpoints
Alerts for Transactions
Set up webhooks for any EVM & Solana wallet to receive real-time notifications on new activity.
One API, every major chain
Ethereum, Base, Solana, Arbitrum and 45+ more networks — queried in a single call.
Ethereum
Base
Solana
Arbitrum
OptimismEthereumBaseSolanaArbitrumOptimismEthereumBaseSolanaArbitrumOptimismEthereumBaseSolanaArbitrumOptimismEthereumBaseSolanaArbitrumOptimismEthereumBaseSolanaArbitrumOptimism
Polygon
Avalanche
BNB Chain
Robinhood
Linea
ScrollPolygonAvalancheBNB ChainRobinhoodLineaScrollPolygonAvalancheBNB ChainRobinhoodLineaScrollPolygonAvalancheBNB ChainRobinhoodLineaScrollPolygonAvalancheBNB ChainRobinhoodLineaScrollPolygonAvalancheBNB ChainRobinhoodLineaScroll
Zora
Celo
Gnosis
Fantom
Aurora
HyperEVMZoraCeloGnosisFantomAuroraHyperEVMZoraCeloGnosisFantomAuroraHyperEVMZoraCeloGnosisFantomAuroraHyperEVMZoraCeloGnosisFantomAuroraHyperEVMZoraCeloGnosisFantomAuroraHyperEVMWhy builders choose the
Transaction Subscriptions API
Ship faster
Go live in minutes, not months
Grab a free key, paste one request, and you're serving portfolio data. No nodes, no indexers, no infra to maintain.
Speed
Fast everywhere your users are
A globally cached edge keeps every query fast, so your app feels instant no matter where your users open it.
Freshness
Balances update in seconds
Balances, positions, and transactions land within seconds of confirmation. Never stale, never guessing.
Scale
Scale from one user to millions
One request spans Solana, Ethereum, Base and 50+ chains. The same endpoint carries your first user and your millionth.
Built for Consumer Scale and Enterprise Reliability
The same infrastructure that runs the Zerion wallet — sized for everything from a first prototype to fintech products in production.
Stay ahead with the Zerion API
New endpoints, chains, and webhooks — straight to your inbox.
Simple, transparent tiers
Start building for free. Upgrade as you scale.
For early prototypes and proofs of concept
Get Started Free- 2K requests / day
- 3 RPS limit
- Chat widget
- Best effort support
For shipping MVP without running any Infrastructure
Start building- Up to 250K requests / month
- 10 RPS
- Telegram group
- Priority support
For apps preparing for launches or already in production
Start building- Up to 1M requests / month
- 25 RPS
- Slack or Telegram channel
- Priority support
Custom pricing & features
For scale-ups & enterprises with high volume or custom needs
Contact salesDeFi Positions, Wallet Portfolio Chart, and Wallet P&L endpoints are limited to 25% of every plan quota and aren’t covered by overages.
What can you build?
Wallets & Stablecoins
Power portfolio views, transaction history, and in-app swaps with one API — across every chain and stablecoin your users hold.
Fintech & Neobanks
Add portfolio charts, PnL, and transaction history to your app — no blockchain node to stand up, no infra to maintain.
AI Agents
Wallet holdings, DeFi positions, and PnL in a single call. Pay per request with x402 on Base — no subscriptions, no keys.
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Trusted by the companies you know
From multichain wallets to onchain apps — teams build on Zerion API.
“Zerion API powers Kraken 2.0 with reliable token balances, P&L, and transaction history through one consolidated integration, making it easier to scale to more users.”
“We've worked with Zerion API since day zero, even before launching Uniswap Wallet. From multichain positions to EIP-7702 batching, they've been key partners.”
“Add a fresh customer quote here — pulled from the cleaned-up testimonials doc.”
“Add a fresh customer quote here — pulled from the cleaned-up testimonials doc.”
Built for developers.
Trusted by enterprises.
Give wallets, AI agents, and consumer apps reliable access to wallets, positions, transactions, and DeFi data across chains.
FAQ
If you have any questions