mailexodus
free forever open source · MIT platform agnostic

leave your email platform. give your agent the playbook.

mailexodus gives your agent the migration plan: what the source can export, what the destination can import, and which flows need human review. Not a checklist. A skill plus a prompt.

agentUse mailexodus skill: Klaviyo → Mailchimp playbook
build the playbook →star on github

reads from: klaviyo · customer.io · mailchimp · activecampaign · brevo · mailerlite · hubspot · 29+ more

0+
source adapters
0
object types normalized
0
open portable schema
$0
forever, MIT licensed
migrating from
Klaviyo
mailexodusopen schema
read · normalize · render
into
Mailchimp
// the difference

everyone hands you a pdf. this gives your agent the route.

The category ships migration “tools” that are really checklists. Export this, rebuild that, good luck with the automations. mailexodus tells your agent what the source can export, what the destination can import, and how to map the portable objects between them. The parts that can be safely automated, are; the rest is flagged before anyone writes.

the usual

migration checklist.pdf

A 40-item list and a weekend of copy-paste. Your flows get rebuilt by hand, from screenshots, hoping every branch survived.

mailexodus

agent playbook

Generates read, map, and write steps for the agent. It also marks destination import gaps, like Mailchimp automations, before the rebuild starts.

// the migration helper

see your migration before you run it.

Pick where you're leaving. mailexodus maps that provider's real API surface to one portable schema, checks what the destination can actually import, and shows exactly what moves cleanly, what a human should review, and what stays behind. A live route check — no signup, no writes.

analyzing Klaviyo…
source modeAutomated adapter
source exports8
Mailchimp imports8
destination gapsautomations
data leaves machineno · dry-run
$npx mailexodus@latest migrate --from klaviyo --to mailchimp --dry-run
agentUse mailexodus skill: Klaviyo → Mailchimp playbook
running…open the Klaviyo migration guide →
// honesty

what moves, and what doesn't.

No tool can move everything, and anyone who says otherwise is selling you the checklist. The real line depends on both APIs: what your old platform exports and what the new one imports.

→ exports + imports cleanly
  • +
    subscribers and profileswith consent state and timestamps preserved
  • +
    custom fields, lists, groups, and tags
  • +
    segments as rulesrewritten for the destination's model
  • +
    HTML templates and campaigns
  • +
    flowstriggers, delays, conditional splits, and sends where APIs expose them
− stays behind
  • ×
    sender reputationit is earned at the new platform, not exported
  • ×
    historical analyticsopens, clicks, and revenue history live in old tools
  • ×
    contacts mid-flightpeople currently inside an automation finish it there
  • ×
    A/B test history and provider-only assets

You see exactly what can transfer, what the destination cannot import, and what needs review. Before you commit, not after.

// how it works

three steps. one schema in the middle.

01

read

Pull contacts, fields, segments, templates, and flow definitions straight from the source platform's API. Dry-run locally before writing anything.

02

normalize

Map every platform to one portable schema. A welcome series is a welcome series, whatever tool drew the boxes.

03

render

Write the normalized graph into the destination and produce a report: moved, partial, skipped, and manual review.

// the standard

one open schema for portable email automation.

The hard part was never reading flows. It's that every platform models them differently. Klaviyo triggers on metrics, Customer.io on events, Mailchimp on lists. mailexodus defines a normalized shape every adapter reads into and writes out of.

read the schema →contribute an adapter →
# a flow, normalized flow: name: "welcome series" trigger: on: subscribed steps: - wait: 2d - send: "email_01" - split: if: opened
// three ways to hand it off

a skill, an MCP server, or a CLI playbook.

Same engine, three front doors. Copy the skill prompt into your agent, connect it over MCP, or inspect the playbook yourself from the terminal.

copy the skill prompt

Paste the skill and route into your agent. It checks what the source can export, what the destination can import, the exact endpoint reference, and where the API boundary forces a manual rebuild.

  • checks source export and destination import coverage
  • returns source and destination endpoint references
  • dry-runs before any destination write
  • flags reputation, analytics, and API gaps as manual
skill + prompt
Use the mailexodus skill.
Route: Klaviyo → Mailchimp
Check source export + Mailchimp import support.
Do not write until the dry-run report is approved.
// adapters

bring your old tool.

Read-side adapters available or in progress. Destination adapters use the same portable schema, so new write targets can be added without rewriting every source.

activecampaignaweberbeehiivbenchmark emailbrevobuttondowncampaignercampaign monitorconstant contactcustomer.iodripemailoctopusflodeskgetresponseghosthubspotlistmonkkitklaviyoloopsmailchimpmailersendmailerlitemailgunmailjetmailtrapmauticmoosendomnisendpostmarkresendsendersendpulsesendgridshopify emailzoho campaignsyour tool? open a pr →
// migration pages

pick the platform you're leaving.

Every supported source has its own page — real API coverage, adapter notes, and a route playbook you can generate against any destination. Plus an alternatives guide for each.

/migrate-from/klaviyo

Migrate from Klaviyo

Automated adapter — move subscribers, lists, segments, custom fields, and more, with an explicit can/cannot-migrate report.

/migrate-from/mailchimp

Migrate from Mailchimp

Automated adapter — move subscribers, lists, tags, segments, and more, with an explicit can/cannot-migrate report.

/migrate-from/customer-io

Migrate from Customer.io

Automated adapter — move subscribers, segments, suppressions, campaigns, and more, with an explicit can/cannot-migrate report.

/migrate-from/active-campaign

Migrate from ActiveCampaign

Automated adapter — move subscribers, lists, tags, custom fields, and more, with an explicit can/cannot-migrate report.

/migrate-from/brevo

Migrate from Brevo

Automated adapter — move subscribers, lists, segments, custom fields, and more, with an explicit can/cannot-migrate report.

/migrate-from/hubspot

Migrate from HubSpot

Automated adapter — move subscribers, lists, segments, custom fields, and more, with an explicit can/cannot-migrate report.

see every migrate-from & migrate-to page →read a sample alternatives page →
// questions

the things you're actually wondering.

Is mailexodus really free?
Yes. It's open source under the MIT license and runs on your own machine. There is no account, no paywall, and no “contact sales” to get a migration report. Sequenzy sponsors the project as the first write destination, but the CLI, the schema, and every source adapter are free to use and fork.
Does my subscriber data leave my computer?
A dry run inspects your source provider and produces a report locally — nothing is written anywhere. Use read-only API keys for inspection, and only add destination write scopes when you've reviewed the report and run --commit yourself.
What happens to my deliverability and sender reputation?
It stays behind, because it has to. Reputation is earned per-platform and can't be exported by anyone. mailexodus is explicit about this: plan domain authentication and a warmup window, and keep the old platform live until the new one is trusted.
Can it actually move my automations and flows?
Where the source API exposes them, yes — triggers, delays, conditional splits, and sends are normalized into the portable schema. Branch logic that an API won't fully reveal is flagged as needs review rather than silently dropped, so you activate it deliberately.
Which platforms can I migrate between?
36+ sources today — Klaviyo, Mailchimp, Customer.io, ActiveCampaign, Brevo, MailerLite, HubSpot, and more. The planner checks both sides of each route: source export coverage and destination import coverage. Run it above for any pair.
Can an AI agent run the migration for me?
Yes. mailexodus ships as an MCP server and a bundled agent skill. An agent can list adapters, inspect source and destination coverage, generate the dry-run report, and stage the read/map/write steps — then hand it to you for approval before anything is committed.
// it's free, it's yours

stop being held hostage by an export button.

Your audience, your automations, your years of work. Give your agent the skill, prompt, and route before you move.

agentUse mailexodus skill: migration playbook + dry-run report
star on github →npm package