Open-source stack for small marketing agencies

TL;DR

• A six-app open-source stack — Mautic, Matomo, Chatwoot, n8n, Castopod, Penpot — replaces HubSpot Marketing Hub, Mailchimp, GA4, Intercom, Zapier, and Figma for a 3–10 person agency.

• At a typical agency setup the SaaS equivalent runs roughly $1,160/month before HubSpot's $3,000 onboarding fee. Six managed apps from us total €54/month.

• Every app on the list is GPL, MPL, AGPL, or MIT licensed. The agency owns the data, the dashboards, and the resell ceiling.

• Mautic, Matomo, Chatwoot, and Castopod each support running one instance per client cleanly. n8n stitches the rest together.

• At €54/month wholesale and €30–50/app retail, ten clients on two apps each works out to roughly €440–820/month gross margin before agency labour.

Who this list is for (and isn't)

This list is for the agency owner who has been running on ad-spend retainers and wants a second recurring-revenue line that doesn't depend on Meta or Google. Web, marketing, growth, or boutique dev shops between three and twenty-five people. Agencies whose clients already pay them for results and would happily pay €30–€50/month per managed tool if it meant the agency, not a US SaaS vendor, owned the relationship.

It is not for solo freelancers below the recurring-revenue threshold — the operational overhead of even a managed stack is more than the margin returns at one or two client accounts. It is not for big agencies with an in-house DevOps function — they already self-host, and the management premium doesn't make sense for them. It is not for the agency that has never been asked "can you also host this for us?" by a client — that question is the buying trigger for everything that follows.

The posts in this category run deeper on the reseller mechanics. This one stays at the level of: which six tools, what each replaces, what the math looks like, and how they fit together. This is our Partners page.

The shortlist

1. Mautic — replaces HubSpot Marketing Hub and Mailchimp

Mautic is the open-source marketing automation platform. Email campaigns, contact management, lead scoring, segmentation, dynamic content, landing pages, drip sequences, behavioural triggers — the things HubSpot Marketing Hub Pro charges $890/month for, and the things Mailchimp Standard adds per-contact pricing to. Mautic does both, with one codebase under GPL v3, run by a foundation that picked up the project from Acquia in 2020.

At a small agency's typical scale — 3 marketers, 5,000 contacts in the database, multi-step nurture flows — Mautic replaces what HubSpot Marketing Hub Pro ($890/month base, three seats, plus a mandatory $3,000 onboarding fee) and Mailchimp Standard ($100/month at 5,000 contacts) would each bill separately. That is a $990/month line item on the agency's books before the first email goes out.

On managed Mautic for client campaigns, the same instance runs at €9/month per client. The agency installs once per client, owns the contact database, sets segmentation rules per brand, and bills the client whatever the agency prices it at. Mautic supports CSV import from HubSpot and Mailchimp exports; the migration path is tedious but real. Best for: agencies that already run drip campaigns for clients and are watching the per-contact line item creep past comfortable.

2. Matomo — replaces GA4

Matomo is the open-source web analytics platform that lets the agency own the data instead of handing it to Google. GPL v3, deployed by the United Nations, by several national governments, and across roughly a million sites. The interface is close enough to GA4 that clients accustomed to one can read the other; the difference is that Matomo runs on infrastructure the agency controls, with no sampling above a few million events, no consent-prompt funnel tax, and no data trip to a US-incorporated analytics warehouse.

GA4 is free in dollars. The cost shows up the first time a client's procurement team asks where the visitor data lives, or a French or Italian or Austrian data protection authority sends a letter about cross-Atlantic transfers, or the agency loses a deal because the prospect's legal team flagged the analytics layer. That cost is real but invisible until it isn't.

For agencies running managed Matomo for client analytics, the wedge is straightforward: install one Matomo per client, give the client a dashboard with their own brand on it, send a monthly report the client owns. Best for: agencies whose clients are starting to ask "where does our visitor data go?" and don't want to write the consent banner copy twice.

3. Chatwoot — replaces Intercom

Chatwoot is open-source customer support software. Live chat widget, shared team inbox, email, social channels (WhatsApp, Facebook Messenger, Instagram, Telegram), a help centre, automation rules, canned responses — the full Intercom-style helpdesk surface, MIT licensed, built by a team in Bengaluru and shipping at a roughly monthly cadence.

Intercom's published pricing in mid-2026: Essential at $29/seat/month on annual billing, Advanced at $85/seat/month, Expert at $132/seat/month, plus $0.99 per Fin AI resolution. A small agency running support for one client on the Advanced plan with three seats is at $255/month before the AI charges land. Five clients on the same setup is $1,275/month. Chatwoot ships the same channel and routing surface under a license that doesn't bill per agent.

The honest gap: Chatwoot's AI agent layer is younger than Fin, and some of the deeper analytics still require building the queries against the Chatwoot data model. For a small agency running tier-one client support across two to ten clients, that gap closes fast. Best for: agencies offering managed customer support as part of an ongoing retainer.

4. n8n — replaces Zapier

n8n is the visual workflow automation platform. Drag a trigger node, connect actions, run on cron or on webhook — the same shape as Zapier with two structural differences. First, the license is fair-code (Sustainable Use License) and the code is on GitHub; the agency owns the workflows as files, version-controlled, exportable as JSON. Second, the pricing model is flat per instance, not per task — a small agency running 50,000 automation tasks a month pays the same as one running 500.

Zapier's task model bites agencies fastest. Professional at $19.99/month (annual) caps at 750 tasks. A four-step Zap firing 200 times a month consumes 800 tasks — already over the entry-tier ceiling. Team at $69/month annual goes to 2,000 tasks. An agency running enrichment, CRM sync, ad-platform reporting, and lead routing across five clients tends to hit five-digit task counts and end up at $250-plus per month, with Zapier overage emails the second-most-clicked thing in the inbox after the client briefs.

On n8n for cross-tool agency workflows, the typical pattern is one shared n8n instance for the agency itself, with workflows segmented by client. Best for: agencies stitching ad platforms to CRMs to client billing systems and feeling the per-task tax compound.

5. Castopod — replaces Anchor and Buzzsprout

Castopod is open-source podcast hosting with a federated twist. AGPL v3, built by Ad Aures in France, Podcasting 2.0 certified, and integrated with ActivityPub — which means the podcast itself becomes a Fediverse account other Mastodon and Pleroma users can follow, comment on, and share. RSS export for Apple Podcasts and Spotify. Built-in analytics that don't ship listener data to a third-party network. Transcripts, chapters, monetisation hooks, and a per-show admin panel.

This is the tool that doesn't have a direct line-item replacement in the brief's HubSpot-Mailchimp-Intercom-Zapier-Figma column, but it shows up on a marketing agency's stack for a real reason: podcasts are how a chunk of the agency's clients now do content marketing. Buzzsprout starts at $12/month and tops out around $24/month per show; Spotify for Podcasters (the Anchor rebrand) is free but locks the listener data behind their platform.

For agencies running podcast production as a service line, Castopod gives every client their own hosted instance with branded RSS, owned analytics, and a federation handle the agency can hand off if the relationship ever changes. Best for: agencies running content-and-podcast retainers for B2B clients, or for the agency that wants a thought-leadership show without renting it from a platform.

6. Penpot — replaces Figma

Penpot is the open-source design and prototyping platform that runs in the browser on open web standards — SVG and CSS instead of a proprietary binary format. MPL-2.0 license, built by Kaleidos out of Spain, version 2.14 as of March 2026 with 45,000+ stars on GitHub. The interface tracks Figma closely enough that a designer can transition in a day; the underlying file format is human-readable SVG, which makes the design-to-code handoff feel less like translation and more like inspection.

Figma's pricing in 2026: Professional at $12/editor/month annual (or $15 monthly, with a recent bump to $16 on some plans), Organization at $45–$55/editor/month annual. For a three-designer agency on Professional, that is $36–$45/month in editor seats. Add Dev Mode for the developers and the bill goes up. The newer per-product seat changes have unevenly affected agencies that work across multiple client organisations and were absorbing the double-billing.

Penpot self-hosted removes the seat tax. The agency runs one instance, invites unlimited editors and viewers, and pays a flat infrastructure cost. Best for: agencies whose Figma bill scales every time a new freelance designer joins a project, or whose clients are starting to ask whether the design files actually belong to them.

How they fit together

The point of running the stack as a stack — not as six unrelated tools — is that the data flows the agency's clients actually want come out of the combinations, not out of any single app. A few patterns earn their keep.

The marketing-automation loop: Mautic + Matomo + n8n.

The support loop: Chatwoot + Mautic.

The podcast loop: Castopod + Matomo + Mautic.

The design loop: Penpot + Mautic.

The client-handoff loop: any combination + n8n.

None of these patterns is fragile in the way the equivalent SaaS-to-SaaS Zapier sequence is fragile. The agency owns each piece, each database, and each API key — and when one app changes a webhook signature, the n8n workflow is one node-edit away from being correct again.

How to start

Picking the whole stack at once is a way to ship none of it. The pattern that works for agencies the team has talked with — and the one we recommend on the trial — is to deploy one app, run it for fourteen days against a real client workload, and only then layer in the next.

For most agencies, the right first app is Mautic. It is the largest line item on the SaaS bill, the easiest conversation to have with a client ("we'll move your email automation to a system you own"), and the most disciplined deployment — Mautic done right covers contact management, drip sequences, and landing pages for at least one full campaign cycle before the next decision lands.

Once Mautic is stable, add Matomo. The pair is the agency's marketing platform — automation plus measurement. The same Mautic landing page now reports on its own conversions; the agency stops paying for two analytics layers (the SaaS-native one and the in-house one a senior strategist usually builds in a spreadsheet).

From there the order is workload-driven. If the agency runs client support, Chatwoot is next. If the agency stitches platforms together for clients, n8n is next. If the agency runs podcast production, Castopod. If the in-house design team is the bottleneck, Penpot.

The trial gives the agency seven days, no card, to try one app end-to-end. Two weeks is enough to know whether the operational shape works for the agency's specific client mix.

Start the 7-day trial  ·  Browse the full catalog  ·  See pricing

FAQ

What stack do small marketing agencies use to replace HubSpot in 2026?

The pattern most often seen: Mautic for marketing automation and email, Matomo for analytics, Chatwoot for live chat and helpdesk, n8n for cross-tool automation, and Penpot for design. Together they replace HubSpot Marketing Hub, GA4, Intercom, Zapier, and Figma. Total managed cost: roughly €45/month for the five-app core, or €54/month with Castopod added.

What is the cheapest open-source alternative to HubSpot Marketing Hub?

Mautic is the closest like-for-like open-source replacement. It covers email automation, drip sequences, lead scoring, segmentation, and landing pages under GPL v3. Self-hosted it is free in licensing but needs a server and operational time. Managed at €9/month per client, it replaces HubSpot Marketing Hub Pro's $890/month base plus the $3,000 onboarding fee.

Is Matomo really a complete GA4 replacement?

For most agency use cases, yes. Matomo covers event tracking, funnels, goals, e-commerce, heatmaps, session recordings, and form analytics under GPL v3. The honest gap is the BigQuery-style raw-data export GA4 ships for free; Matomo's equivalent is a paid plugin or direct database access. At a few sites in, the trade favours Matomo.

Can Chatwoot replace Intercom for B2B SaaS support?

For most agency-supported B2B SaaS workloads, yes. Chatwoot covers live chat, shared inbox, email, WhatsApp, Telegram, Instagram, automation rules, and a help centre under the MIT license. The honest gap is the maturity of Chatwoot's AI agent versus Intercom Fin. For tier-one support across two to ten client accounts, the gap is small.

Is n8n cheaper than Zapier at high task volumes?

Yes — by a wide margin. Zapier's Professional plan charges $19.99/month for 750 tasks; an agency running 10,000 tasks monthly often lands at $250–$500. n8n is priced per instance, not per task, so the same workload runs on a single €9/month managed instance. The crossover happens around 1,500 tasks per month.

What's the best open-source workflow automation tool for agencies?

n8n is the strongest fit. Visual workflow editor, fair-code license, JSON workflow export, 400+ integrations, and a pricing model that scales by instance rather than per task. For agencies stitching CRMs, ad platforms, billing systems, and client dashboards together, a single managed n8n instance at €9/month carries the workload most agencies need.

Is Penpot production-ready for client design work in 2026?

Penpot reached version 2.14 in March 2026, with 45,000+ GitHub stars and active commits. The core design and prototyping surface — components, libraries, CSS Grid, flexbox, prototyping — is production-ready. The plugin ecosystem is smaller than Figma's, and performance on very large design systems lags. For most agency client work, Penpot ships.

Does Castopod support Apple Podcasts and Spotify?

Yes. Castopod publishes standard RSS feeds compatible with Apple Podcasts, Spotify, Pocket Casts, Overcast, and every directory built on the open podcast protocol. The bonus over hosted SaaS platforms: Castopod's ActivityPub layer also turns each show into a Fediverse account, so listeners on Mastodon can follow and comment directly from their own server.

How much does it cost to run Mautic for a marketing agency?

Self-hosted Mautic costs the price of a server, an email relay, and the operational time to keep it patched — typically €100–€280/month effective for one production instance. Managed Mautic from us is €9/month per client instance, which includes the server, patches, backups, and the on-call. The math favours managed at three clients in.

Why would an agency choose self-hosted open-source over SaaS partner programs?

Three reasons agencies cite. Ownership: the agency holds the data and the client relationship, not the SaaS vendor. Margin: wholesale at €9/app, retail at €30–50/app is a healthier recurring line than a SaaS reseller commission. No upfront cost: most SaaS partner tiers require annual commitments or partner fees small agencies can't absorb.

Why not just self-host this stack on a VPS with Coolify?

If the agency has an in-house developer who enjoys infrastructure, Coolify on a $24 production-class VPS is a genuinely good path. The trade is real: setup runs five to ten hours, monthly upkeep is one to two hours, and the on-call falls on whoever is comfortable getting paged. For agencies with that person on staff, the math favours self-hosting. For agencies that would rather have that person on client work, managed makes the trade obvious.

Can I run one Mautic for all my clients, or do I need one per client?

One per client is the cleaner pattern. Mautic supports multi-tenant deployments but the contact database, segmentation, and email-domain reputation get tangled when two clients share an instance. At €9/month per client, the per-instance approach also gives the agency a clean line-item to bill against. The same logic applies to Matomo and Chatwoot.

Can I migrate from HubSpot to Mautic without losing data?

Yes — and Mautic's import path is mature. Export contacts from HubSpot as CSV with all custom fields. Import into Mautic with field mapping. Email templates, workflows, and segmentation rules need to be rebuilt manually; that work is tedious but bounded. Most agencies finish a single-client migration in one to two working days.

How long does it take to switch from Zapier to n8n?

Most simple Zaps rebuild in n8n inside an hour each. Complex multi-step workflows with custom code or rare integrations take a day. A full agency switch — typically twenty to fifty active workflows across five clients — completes in one to two working weeks of focused effort. The workflows then live as JSON files the agency owns.

How long does each app take to set up?

Activation through the trial is fast — most apps reach a working dashboard within minutes; some complex setups (custom domains, email-relay verification, OAuth handoff with a client's identity provider) sometimes need a human touch from support. The chat is open during business hours and on call after; the first reply is a named engineer, not a queue.

Can clients access their own Matomo or Mautic dashboard directly?

Yes. Both apps support multiple user roles with per-user permissions. Most agencies create a branded subdomain per client (analytics.client.com or marketing.client.com), give the client read-only or limited-edit access, and keep admin rights with the agency. The client sees their own dashboard, with their own brand, on infrastructure the agency controls.

Where in the world can these apps be hosted?

Across 21 datacenter locations on six continents. The agency picks the region closest to its clients' end users. Latency to a London, New York, Frankfurt, Singapore, or Sydney instance is in the low tens of milliseconds from the corresponding home market. Each app can sit in a different region if the agency's client base is geographically spread.

Are these open-source tools maintained well enough for production use?

Yes, all six have active development. Mautic is GPL v3 with a community foundation behind it and regular minor releases. Matomo backs roughly a million sites including major institutional deployments. Chatwoot ships at a monthly cadence under MIT. n8n is well-funded and ships frequently. Castopod is grant-funded and Podcasting 2.0 certified. Penpot crossed 45,000 GitHub stars with version 2.14 in March 2026.

What does “resells well” actually look like in practice?

Wholesale at €9/month per app, retail at €30–50/app/month to the client. The agency adds branded dashboards, monthly reports, and the support relationship; the client gets a managed tool with a familiar invoice. Across ten clients on two apps each, the gross margin lands around €440–820/month before agency labour. The deeper economics are in the agency reseller posts queued for this quarter.

What about the AI features I get with HubSpot and Intercom?

The Mautic and Chatwoot AI layers are younger than the equivalent HubSpot Breeze and Intercom Fin features. For automated send-time optimisation, lead scoring, and chat-response drafting, the gap closes year over year. For an agency that needs a specific AI feature today, the honest answer is to keep that one SaaS line item and replace the rest. Most agencies find the cost-versus-feature trade favours replacing more than they expected.

What happens if I want to leave?

The apps are open source. The data exports cleanly — Mautic via SQL dump and CSV, Matomo via its data export tool, Chatwoot via API, n8n via JSON workflow export, Castopod via OPML and standard RSS, Penpot via .penpot file. Backups run daily. The agency owns the data, and the migration path is the same whether moving to a self-host setup, another managed provider, or back to a SaaS.

What to do this week

Pick the largest line item on the agency's current SaaS subscription page. If that is HubSpot, the first app to trial is Mautic. If it is Intercom, Chatwoot. If it is Zapier overage emails, n8n. Sign up for the 7-day trial. Deploy one app, run it against one client account for two weeks, and decide.

The cleanest evaluation week looks like this. Day one: deploy the app and connect the agency's domain. Day two: import the working data — contacts for Mautic, the tracking snippet for Matomo, the chat widget code for Chatwoot. Day three through seven: run the agency's existing workload through the new tool in parallel with the SaaS. By the end of the week, the agency has enough operational evidence to decide whether to switch, switch partially, or wait. Two weeks lets a real campaign cycle complete on the new stack — usually enough to settle the question.

The recurring-revenue line that doesn't depend on Meta or Google is the one the agency builds out of tools the agency owns. The six apps on this list are the most boring, most operationally proven, and most resellable ways to get started.