Helius RPC

Overview

Helius is the dominant production RPC provider on Solana. Beyond standard JSON-RPC (getBalance, sendTransaction, etc.), Helius layers on a set of APIs that the base Agave validator does not expose: the DAS API (one unified query surface for NFTs, compressed NFTs, and SPL tokens), enhanced transaction parsing (human-readable swap/transfer/mint events), real-time webhooks (push deliveries when watched accounts move), and getPriorityFeeEstimate (the de-facto way to size compute-unit-price on mainnet). If you are building anything beyond a toy, you will almost certainly call at least two of these.

When to use this skill

• The user mentions Helius, Helius RPC, DAS API, Helius webhooks, or getPriorityFeeEstimate.
• The user wants to fetch a wallet's NFTs / cNFTs / tokens in one call (use DAS, not getTokenAccountsByOwner).
• The user needs a push notification when a Solana account changes state.
• The user is sending mainnet transactions and asks about priority fees / CU price / landing rate.
• The user needs parsed/decoded transaction history (who swapped what, mint events, sales) rather than raw byte instructions.

Prerequisites

• Helius account + API key from https://dashboard.helius.dev (the free Developer tier is fine to start; the credit and RPS limits scale on Pro / Business plans).
• Node 20+ (the SDK targets modern Node and uses native fetch).
• One of:
• npm install helius-sdk@^2.2.2 — typed client, namespaces for webhooks, enhanced, tx, ws, etc. Built on @solana/kit (the v1.x line used @solana/web3.js).
• Or plain fetch against the JSON-RPC endpoint — no dependencies, works in Cloudflare Workers / Deno / Bun without polyfills.
• For webhooks: a public HTTPS endpoint (Cloudflare Worker, Vercel function, ngrok tunnel for dev). Helius will not POST to localhost.

Workflow

1. Get an API key

Sign in at https://dashboard.helius.dev, create a project, copy the API key. Mainnet and devnet share the same key — you switch by changing the endpoint hostname, not the key.

2. RPC endpoint URL format

Mainnet:  https://mainnet.helius-rpc.com/?api-key=YOUR_KEY
Devnet:   https://devnet.helius-rpc.com/?api-key=YOUR_KEY

# Dedicated staked-connection endpoint (Pro+) for higher landing rate on sendTransaction:
Staked:   https://staked.helius-rpc.com/?api-key=YOUR_KEY

The endpoint accepts every standard Solana JSON-RPC method plus Helius extensions. Drop it into @solana/web3.js new Connection(url) or @solana/kit createSolanaRpc(url) unchanged.

3. DAS API — NFT / token queries

DAS unifies regular NFTs, compressed NFTs, and (with showFungible: true) SPL tokens behind one method family on the standard RPC endpoint. The most useful methods:

• getAssetsByOwner — every asset a wallet owns, paginated.
• getAsset — one asset by mint or cNFT ID.
• getAssetsByGroup — every asset in a collection (groupKey: "collection").
• searchAssets — flexible filter (creator, royalty, jsonUri, etc.).

Pagination is 1-indexed page numbers, max limit: 1000. Loop until items.length < limit. See scripts/get-assets.ts.

4. Webhook setup

Create a webhook with the REST API or helius.webhooks.createWebhook(...). Key fields:

• webhookURL — your HTTPS endpoint (must return 200 within 1s).
• webhookType — "enhanced" (Helius parses to a typed event) or "raw" (full Solana tx). enhancedDevnet / rawDevnet for devnet. Enhanced webhooks drop failed transactions; raw webhooks include both.
• accountAddresses — up to 100,000 addresses to watch.
• transactionTypes — filter to specific parsed types (SWAP, NFT_SALE, TRANSFER, ..., or ANY). Only meaningful for enhanced.
• authHeader — a secret string. Helius echoes this value back in the Authorization header of every webhook POST. Your handler must compare it before processing.

5. Webhook handler

The handler must:

1. Verify the Authorization header equals the authHeader you registered.
2. Return 200 within 1 second (Helius timeout). Do heavy work async — push onto a queue, then respond.
3. Be idempotent — Helius retries up to 3 times with a 1s gap on 5xx / timeout / non-403 4xx. Deduplicate on signature.

See scripts/webhook-handler.ts (Cloudflare Worker).

6. Enhanced transaction parser

For backfill / one-shot parsing (not push), POST signatures to:

POST https://api-mainnet.helius-rpc.com/v0/transactions
Body: { "transactions": ["sig1", "sig2", ...] }  // up to 100 per call

Same shape as the enhanced-webhook payload — description, type, source, nativeTransfers, tokenTransfers, events, accountData, etc. Useful for catching up after webhook downtime.

7. Priority fee estimation

getPriorityFeeEstimate returns a recommended `microLamports` value for ComputeBudgetProgram.setComputeUnitPrice. Call it with either:

• accountKeys: [pubkey, ...] — the writable accounts your tx touches, or
• transaction: <base58-or-base64 serialized tx> — Helius will extract accounts itself.

Pass options.recommended: true for a single-number answer, or options.includeAllPriorityFeeLevels: true to get the full { min, low, medium, high, veryHigh, unsafeMax } histogram. See scripts/priority-fee.ts.

8. Free vs paid tiers — rate limits (as of 2026)

• Developer (free): ~10 RPS, 1M credits/mo, no dedicated nodes.
• Pro / Business / Professional: higher RPS, staked-connection endpoint, larger webhook quotas, dedicated nodes available.

Each webhook delivery costs 1 credit regardless of whether your endpoint succeeds. DAS calls cost more credits than vanilla RPC. Check the live pricing page before relying on these numbers.

Common pitfalls

• Mixing devnet and mainnet — same API key, different hostnames. Sending a mainnet transaction to devnet.helius-rpc.com will give you a confusing "blockhash not found" because the blockhash you fetched is from the other cluster. Always read your endpoint string back to yourself.
• No backoff on 429 — the free tier rate-limits aggressively. Wrap every call in retry-with-exponential-backoff. The SDK does not do this for you.
• Webhook returns non-200 or takes >1s — Helius retries 3 times with a 1s gap, then drops the event forever. Acknowledge first (return 200), process after. In Cloudflare Workers, use event.waitUntil() to defer work past the response.
• Forgetting DAS pagination — getAssetsByOwner caps at limit: 1000. A whale wallet with 10k NFTs returns only the first 1k unless you loop page: 1, 2, 3, .... Stop when items.length < limit.
• Treating `priorityFeeEstimate` as lamports — it is microLamports (1e-6 lamports). You pass it directly to ComputeBudgetProgram.setComputeUnitPrice({ microLamports }). Multiplying by 1e6 is a common and very expensive mistake.
• Webhooks won't replay missed events — there is no historical replay endpoint for past webhook deliveries. If your handler is down, those events are gone. On boot, backfill the gap with getSignaturesForAddress + the enhanced transactions parser API (step 6) over your watched accounts since the last processed slot.
• Enhanced webhook drops failed tx — if you need to see reverted swaps or failed mints, use webhookType: "raw" (or check transactionError field).
• `authHeader` is plaintext, not HMAC — anyone who can read your dashboard or webhook record can replay requests. Treat it like a bearer token: long, random, rotated. For high-value flows, also gate by source IP at your edge / WAF.

References

• Helius docs hub: https://www.helius.dev/docs
• DAS API: https://www.helius.dev/docs/das-api
• Priority Fee API: https://www.helius.dev/docs/api-reference/priority-fee/getpriorityfeeestimate
• Webhooks: https://www.helius.dev/docs/api-reference/webhooks
• Enhanced Transactions: https://www.helius.dev/docs/api-reference/enhanced-transactions/gettransactions
• SDK GitHub: https://github.com/helius-labs/helius-sdk
• Dashboard: https://dashboard.helius.dev
• Discord (fastest support for quota / outage questions): https://discord.gg/helius

Example scripts

See scripts/get-assets.ts, scripts/webhook-handler.ts, scripts/priority-fee.ts.