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Troublor merged 2 commits into from
Jul 8, 2026
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doc: document public RPC request body size limits #77

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doc: document public RPC request body size limits
Troublor Jul 8, 2026
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doc: apply prettier formatting to RPC body-limit tables
Troublor Jul 8, 2026
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13 changes: 13 additions & 0 deletions docs/dev/read/overview.md
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Expand Up @@ -117,6 +117,19 @@ All available methods are subject to rate limiting based on two criteria:

User limits are dynamically updated in response to individual behavior.

## Request Body Limits

The public RPC endpoint caps the size of the request body, and the cap depends on the method being called:

| Method class | Maximum body size |
| --------------------------------------------------------------------------------------------------- | ----------------- |
| Transaction submission (`eth_sendRawTransaction`, `realtime_sendRawTransaction`) | 2.5 MiB |
| Large reads and simulations (`eth_call`, `eth_callMany`, `eth_createAccessList`, `eth_estimateGas`) | 1.5 MiB |
| All other methods | 128 KiB |

The higher limits for simulation methods let you estimate gas for or simulate large contract deployments, whose initcode can exceed the 128 KiB default.
A request whose body exceeds the applicable limit is rejected with HTTP `413` and RPC error `-32099` (`payload too large`) — see [Error Codes](rpc/error-codes.md).

## Related Pages

- [Realtime API](realtime-api.md) — use-case guide for streaming data and instant receipts
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19 changes: 10 additions & 9 deletions docs/dev/read/rpc/error-codes.md
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Expand Up @@ -4,15 +4,16 @@ description: MegaETH JSON-RPC error codes — HTTP status codes, RPC error codes

# Error Codes

| HTTP Error Code | RPC Error Code | Error Message | Explanation | Mitigation |
| --------------- | -------------- | -------------------------------------------------------------- | --------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| 400 | -32700 | `parse error` | The request body contains invalid JSON. | Check the request format and ensure valid JSON syntax. |
| 403 | -32601 | `rpc method is not whitelisted` | The requested RPC method is not allowed by the proxy configuration. | Use only whitelisted RPC methods. Contact MegaETH if you need access to additional methods. |
| 400 | -32019 | `block is out of range` | The requested block number is out of range. | Check the block number and ensure it's within the valid range. |
| 500 | -32020 | `backend response too large` | The backend response is too large. | Reduce the scope of the request or contact MegaETH for assistance. |
| 429 | -32021 | `over network traffic limit, retry in X seconds` | The user is incurring too much network traffic. | Wait for the specified number of seconds before retrying. Reduce the number of requests sent per second. |
| 429 | -32022 | `over compute unit limit, retry in X seconds` | The user is incurring too much computation on the backend RPC server. | Wait for the specified number of seconds before retrying. Reduce the number of requests sent per second. |
| 200 | -32000 | `permanent error forwarding request context deadline exceeded` | The API proxy cannot connect to the backend RPC server. | Pause for a while and retry. Notify MegaETH if the error persists. |
| HTTP Error Code | RPC Error Code | Error Message | Explanation | Mitigation |
| --------------- | -------------- | -------------------------------------------------------------- | --------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------- |
| 400 | -32700 | `parse error` | The request body contains invalid JSON. | Check the request format and ensure valid JSON syntax. |
| 413 | -32099 | `payload too large` | The request body exceeds the size limit for the method being called. | Stay within the body-size limit for the method class. See [Request Body Limits](../overview.md#request-body-limits). |
| 403 | -32601 | `rpc method is not whitelisted` | The requested RPC method is not allowed by the proxy configuration. | Use only whitelisted RPC methods. Contact MegaETH if you need access to additional methods. |
| 400 | -32019 | `block is out of range` | The requested block number is out of range. | Check the block number and ensure it's within the valid range. |
| 500 | -32020 | `backend response too large` | The backend response is too large. | Reduce the scope of the request or contact MegaETH for assistance. |
| 429 | -32021 | `over network traffic limit, retry in X seconds` | The user is incurring too much network traffic. | Wait for the specified number of seconds before retrying. Reduce the number of requests sent per second. |
| 429 | -32022 | `over compute unit limit, retry in X seconds` | The user is incurring too much computation on the backend RPC server. | Wait for the specified number of seconds before retrying. Reduce the number of requests sent per second. |
| 200 | -32000 | `permanent error forwarding request context deadline exceeded` | The API proxy cannot connect to the backend RPC server. | Pause for a while and retry. Notify MegaETH if the error persists. |

## Related Pages

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7 changes: 7 additions & 0 deletions docs/dev/send-tx/gas-estimation.md
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Expand Up @@ -75,6 +75,13 @@ There are two workarounds:
For reference, standard Ethereum node software (geth, reth) defaults to 50M, and providers like Alchemy support up to 550M.
See the [RPC Providers](../tooling.md#rpc-providers) table for providers that support MegaETH.

### Request Body Size for Large Deployments

Estimating gas for a large contract deployment sends the full initcode in the request body.
To accommodate this, the public RPC endpoint allows `eth_call`, `eth_callMany`, `eth_createAccessList`, and `eth_estimateGas` bodies up to **1.5 MiB** — well above the 128 KiB limit applied to ordinary read methods.
A request that exceeds this limit is rejected with HTTP `413` / `-32099` (`payload too large`).
See [Request Body Limits](../read/overview.md#request-body-limits) for the full breakdown.

## Toolchain Configuration

### Foundry
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