Mailchimp holds the higher mean on campaign and automation (7.0 vs 6.0; 5 judges lean Mailchimp, 1 tie), deliverability (6.8 vs 3.8; 6 lean Mailchimp), list data control (7.0 vs 4.7; 6 lean Mailchimp), integrations (7.7 vs 5.8; 5 lean Mailchimp, 1 tie) and pricing transparency (5.3 vs 2.0; 6 lean Mailchimp). Klaviyo's higher mean is sovereignty, 1.8 vs 1.5, with 2 judges leaning Klaviyo, 0 leaning Mailchimp and 4 ties; Klaviyo's data residency reads EU optional against Mailchimp's US default. Consent and proof is the genuine split: 5.2 vs 5.5 with 3 judges leaning each way. The weighted totals the table lists — CRM manager 5 vs 6.7, deliverability engineer 5.2 vs 6.3, data-protection officer 3.8 vs 4.6, integrator 4.3 vs 6.2, skeptic 3.3 vs 5.7 — put the higher figure on Mailchimp's side. No overall winner is declared: the lean differs by criterion, and that difference is the answer.
Choose Klaviyo if
You need the option to keep contact data in the EU — Klaviyo's data residency is recorded as EU optional, Mailchimp's as US default.
Your contract terms must allow hosting wherever the vendor or its subprocessors maintain facilities — Klaviyo's processing agreement permits that, while Mailchimp's captured pages show US hosting as the fixed default with no EU option on those pages.
You weight sovereignty heavily in your scoring — Klaviyo's sovereignty mean is 1.8 against Mailchimp's 1.5, with 2 judges leaning Klaviyo, 0 leaning Mailchimp and 4 ties.
Your legal screen flags vendors whose subprocessor exposure is recorded as US Cloud Act — Mailchimp's attribute reads US Cloud Act; Klaviyo's is recorded as unknown.
Choose Mailchimp if
You need deliverability you can check before committing — deliverability means run 6.8 vs 3.8, with 6 judges leaning Mailchimp and 0 leaning Klaviyo.
You must be able to take your whole list with you — Mailchimp documents a whole-account export as a zip, and list data control runs 7.0 vs 4.7 with 6 judges leaning Mailchimp.
You need published plan prices before signing — the captured Klaviyo pages state no paid prices, only scaling by contact count and channels with a custom enterprise quote; pricing transparency runs 5.3 vs 2.0 with 6 judges leaning Mailchimp.
Your stack runs on Salesforce — Mailchimp states a two-way Salesforce sync among its 300+ integrations, and integrations leans 5 judges to Mailchimp with 1 tie.
You build branching customer journeys — Mailchimp's journey builder offers conditional and percentage splits, and campaign and automation runs 7.0 vs 6.0 with 5 judges leaning Mailchimp and 1 tie.
Read this comparison as one judge. Each weighs the same scores by what they care about.
The CRM Manager
Owns the lifecycle programme and measures it. Wants segmentation on real behaviour, journeys that branch, and testing that reports significance rather than a bigger number. Treats a tool that can only broadcast as a mailing list with invoicing.
Klaviyo
Mailchimp
This judge's pick
Criterion by criterion
Campaigns & automation
Klaviyo
Behavioural segmentation is the strongest thing on these pages: real-time segments on purchase history, browsing, predictive churn risk, CLV and next order date, unlimited conditions, no lookback limits, plus 60+ prebuilt flows and 150+ templates across email, SMS and push. What I found no public information on is A/B testing of any kind, journey branching, or holdout groups for measurement — the parts a lifecycle programme is actually judged on.
Mailchimp
The flow map with conditional and percentage splits, triggers filterable by segment conditions, event entry through the events endpoint and an API trigger for journeys is a genuine lifecycle tool, with dynamic content documented for the higher plans. But I found no public information on A/B testing of any kind, no significance reporting and no send-time optimisation, so the measurement half of a lifecycle programme has nothing published to stand on.
Deliverability infrastructure
Klaviyo
The published guide covers bounce types, spam traps and blacklists, sending infrastructure, the complaint rate mailbox providers treat as elevated (1 in 1,000), and a 30-day dedicated-IP warm-up — more documented hygiene than most vendors show. But I found no public information on SPF, DKIM or DMARC setup, custom sending domains, or automatic hard-bounce suppression, so the authentication layer of the story rests on nothing quotable.
Mailchimp
Authentication is documented properly — DKIM as two CNAME records and DMARC as a TXT record, with an automated setup path — and dedicated IPs carry a documented warm-up of roughly 30 days, while soft/hard bounce categorisation from SMTP replies factors engagement into cleaning decisions. Complaint-loop handling, inbox-placement testing and published list-hygiene guidance are unevidenced, and bounce reasons are viewable one address at a time, held only 30 days, with bulk export ruled out.
Consent, proof & tracking limits
Klaviyo
Consent is treated seriously: signup forms geo-targeted to EU and UK visitors, every form submission automatically timestamped and version-labelled into a consent log, segmentation by consent status, suppression of profiles without valid consent, and per-person export and deletion tools. I found no public information on double opt-in as a product default, one-click unsubscribe across lists, or turning open and click tracking off — pixel-free sending is likewise not something the captured pages describe.
Mailchimp
The proof side is genuinely strong: a plain-text version of the signup form with its GDPR fields is recorded per contact and viewable on the profile, editing a checkbox invalidates prior consent, and the confirmation mail is customisable. Double opt-in is offered per audience rather than being the documented default and works only on the vendor's own signup forms, and I found no public information on switching open or click tracking off per campaign or otherwise.
List ownership, import & exit
Klaviyo
Individual records in the unified profiles can be found, exported and deleted, a list of deleted profiles is kept as proof of deletion, and the data processing agreement commits to deleting remaining copies within 90 days of contract end with return on request. What I found no public information on is bulk export of engagement history, campaigns and templates in open formats, or migration tooling — so exit looks per-person rather than per-account.
Mailchimp
Account export is documented as a zip of audiences, campaign content, template content, contact events and reporting data in CSV, with permanent deletion and a forget action per contact — subscribers, engagement history and templates all leave in open formats. The exit is metered though: one export at a time and only one per 24 hours, builds running minutes to days, contact exports running per audience, and activity history capped at the previous 180 days of aggregated stats.
Integrations & API
Klaviyo
The connection surface is real: more than 350 prebuilt integrations, a native Shopify integration used by 117,000+ Shopify customers, and developer tools spanning APIs, webhooks, SDKs and warehouse syncs. But the API terms set rate limits at Klaviyo's sole discretion, reserve the right to modify the APIs or cease support without notice, and allow termination at any time for any reason — I found no public information on documented rate limits, a sandbox, or a deprecation policy, and building a programme on those terms is a risk I would have to price in.
Mailchimp
Marketing and transactional sending each have documented APIs, events flow in through the events endpoint and the journey trigger and out through list and account webhooks, batch operations exist, and named integrations include a stated two-way sync with Salesforce plus Shopify, Square and Stripe. Webhook retries and a sandbox are not evidenced, and rate limits are documented only for individual endpoints, which holds this below the top.
European sovereignty
Klaviyo
Klaviyo, Inc. of Boston is the contracting entity, the agreement permits storing and processing customer data wherever Klaviyo or its subprocessors maintain facilities, and lawful transfers rest on the EU-US Data Privacy Framework and standard contractual clauses. A subprocessor list is published and transfer-impact-assessment support is offered, but I found no public information on EU hosting, an EU contracting entity, or where subscriber data and behavioural tracking actually reside — weighed heavily as this buyer weighs it, that sits near the bottom.
Mailchimp
The contracting entity is The Rocket Science Group LLC under Intuit Inc. in the US, US hosting is the fixed default with no EU option anywhere on the captured pages, and no subprocessor list is published on the vendor's own pages. Standard contractual clauses in the data processing addendum and annual Data Privacy Framework certification state a transfer basis, and under that basis session replay through US providers, export files hosted with Google and named third-party API providers all touch the chain — this survives, if at all, on a transfer argument rather than sovereignty.
Pricing transparency
Klaviyo
The free tier is precisely quantified — up to 250 active profiles, 500 emails per month, mobile messaging worth 5 $ per month, Composer usage worth 5 € per month — but the captured pricing pages state no prices at all for paid tiers, only that they scale by contact count and channels with a custom enterprise quote. I cannot compute a real invoice for any list above 250: no contact-tier prices, no overage rates, no VAT treatment, and the promised absence of send or profile limits after upgrading is the only limit statement there is.
Mailchimp
Monthly from-prices and send limits are public per plan — Standard at up to 6,000 emails a month, Premium at 150,000 — and the comparison table shows flow points, audiences, seats and feature boundaries per tier. The captured pages give different figures for the Essentials and Standard monthly prices (€11.50 against €11.34, and €17.45 against €17.68), the overage is stated only as extra costs with no rate, and I found no public information on the Premium tier's price, SMS add-on pricing, or VAT treatment.
Sovereignty, side by side
Dimension
Klaviyo
Mailchimp
Legal entity
Not determined
Not determined
Ownership
Not determined
Foreign-controlled
Data residency
Not determined
Not determined
Subprocessors
Not determined
Not determined
Facts, side by side
Only facts both products carry under the same definition — anything else would not be a fair row.