# Overview (https://docs.axelar.dev/infrastructure/verifiers)



Before Axelar approves a cross-chain message, it checks that the message really happened on its source chain. Who does that checking depends on how the source chain is connected to Axelar.

|                             | Consensus chains                                                      | Amplifier chains                                                                        |
| --------------------------- | --------------------------------------------------------------------- | --------------------------------------------------------------------------------------- |
| Verified by                 | Axelar validators                                                     | Amplifier verifiers                                                                     |
| Must be an Axelar validator | Yes                                                                   | No                                                                                      |
| Software                    | `vald` and `tofnd`, alongside your validator's `axelard`              | `ampd`, `tofnd` and a handler per chain                                                 |
| How you join                | Register as a chain maintainer for each chain                         | Bond AXL, register chain support and get authorized                                     |
| Guide                       | [Verify consensus chains](https://docs.axelar.dev/llms.mdx/infrastructure/verifiers/consensus-chains/content.md) | [Become an Amplifier verifier](https://docs.axelar.dev/llms.mdx/infrastructure/verifiers/amplifier/verifier-onboarding/content.md) |

## Consensus chains [#consensus-chains]

Consensus chains are the EVM chains connected to Axelar before Amplifier. Axelar validators verify them as part of their validator duties: each validator chooses which chains to support, runs a node for each of them, and registers as a maintainer of those chains. Its `vald` process then votes on the chain's events.

To verify consensus chains, first [set up your Axelar validator](https://docs.axelar.dev/llms.mdx/infrastructure/validators/content.md), then follow [Verify consensus chains](https://docs.axelar.dev/llms.mdx/infrastructure/verifiers/consensus-chains/content.md).

## Amplifier chains [#amplifier-chains]

Chains connected through [Amplifier](https://docs.axelar.dev/llms.mdx/infrastructure/content.md#a-cross-chain-protocol-amplifier) each have their own verifier set. Verifiers run `ampd`, which votes on source-chain events and signs outgoing messages for the chains they support. Being an Axelar validator is not required; if you run both, use separate Axelar nodes and `tofnd` instances for each.

To verify Amplifier chains, follow [Become an Amplifier verifier](https://docs.axelar.dev/llms.mdx/infrastructure/verifiers/amplifier/verifier-onboarding/content.md).

## External chain nodes [#external-chain-nodes]

Both kinds of verification need your own node for each chain you support. See [External Chain Nodes](https://docs.axelar.dev/llms.mdx/infrastructure/chain-nodes/content.md) for why that node should be your own, and for setup guides for each chain.


---

All pages of these docs, as Markdown: https://docs.axelar.dev/llms.txt