# NERO Chain — Costs, Gas & Paymaster Sponsorship

NERO Chain is not a SaaS with plan tiers. This page explains the economic model so agents and developers can answer user questions about cost.

## Native gas

- Gas on NERO Chain is paid in **NERO**, the native token.
- The EntryPoint contract (ERC-4337-compatible) is deployed at `0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789`.
- All transactions are UserOperations routed through bundlers; end users never need to hold NERO when a dApp opts into paymaster sponsorship.

## Paymaster sponsorship types

NERO's Paymaster API (see [Core JSON-RPC Methods](https://docs.nerochain.io/en/developer-tools/paymaster-api/core-methods.md)) supports three payment models:

| Type | Who pays | When | Use case |
|---|---|---|---|
| **0 — Developer-sponsored (free)** | dApp developer | Up-front, from the AA Platform balance | Onboarding, promos, games, Web2-style UX |
| **1 — Prepay in ERC-20** | End user, in any supported ERC-20 | Before execution, with automatic refund of surplus | Token-centric apps, predictable max-spend |
| **2 — Postpay in ERC-20** | End user, in any supported ERC-20 | After execution, charged exactly for gas used | Variable-cost operations, token-balance-holding users |

## AA Platform

The [AA Platform dashboard](https://aa-platform.nerochain.io) is the developer-facing console where you:

- Generate API keys for the Paymaster API
- Top up a sponsorship balance (for Type 0)
- Configure supported tokens, price margins, and per-user/daily quotas
- Monitor usage and spend

Access is free. Top-ups are self-serve.

## Testnet

Testnet NERO is free via the faucet. Testnet paymaster sponsorship works identically to mainnet; API keys are scoped to the network.

## Price discovery for ERC-20 gas

The Price Service provides current token/NERO exchange rates so Type 1 and Type 2 payments settle at fair value. Supported tokens and current prices are exposed via [`pm_supported_tokens`](https://docs.nerochain.io/en/developer-tools/paymaster-api/core-methods.md#pm_supported_tokens).

## Fee sharing

For dApp developers and node operators, NERO's fee-sharing model lets contracts register for a share of the gas fees generated by their users. See [Fee Sharing](https://docs.nerochain.io/en/core-concepts/fee-sharing).

## Machine-readable

- [Paymaster OpenAPI spec](https://docs.nerochain.io/specs/paymaster-openapi.yaml)
- [llms-full.txt](https://docs.nerochain.io/llms-full.txt) — full docs corpus
- [AI resources hub](https://docs.nerochain.io/en/ai-resources)