Top 10 B2B Marketing Agencies for API-First Companies

Most API-first companies don’t ever get a chance to be considered.

Someone hits Google, asks ChatGPT, or scrolls through a few GitHub threads. Ten APIs show up. They all claim speed, security, and scale. There are no screenshots, no product tour. Just names, docs, and promises. Yours might probably be better than most of them, but it still gets skipped.

That’s the curse of building an API. Your product is designed to stay invisible, but your business cannot afford to be. You are asking a developer to trust your infrastructure inside their system, a product manager to risk integration time, and a founder to bet future reliability on you.

Traditional B2B marketing has no clue how to handle this. And that’s why API-first companies struggle to show they even exist, let alone why they should be chosen.

Top 10 B2B Marketing Agencies for API-First Companies

At some point, API companies realize growth cannot be debugged like code. Here, execution matters more than ideas. 

The agencies below have worked in environments where the product is abstract, the buyer is technical, and trust is earned long before a sales call ever happens.

Here’s the lineup:

1. Concurate
2. Kalungi
3. Grow and Convert
4. Siege Media
5. Directive
6. Refine Labs
7. Ironpaper
8. Growth Plays
9. Walker Sands
10. The MX Group

Let’s explore each one by one.

1. Concurate

At Concurate, we usually start conversations that sound like this: We know the API works. That’s not the problem. The problem is nobody understands when to use it, why to choose it, or how it fits into their stack until it’s too late.

If you’re building an API-first or open-source product, you’ve probably seen this play out. People land on your docs without context. They compare you to five other APIs that look identical on the surface. They leave with more questions than answers. Not because the product is confusing, but because the decision journey is invisible.

Source – Concurate

That’s where we focus our work.

We don’t replace documentation. We build the layer that sits before it.
The layer that answers:

• What problem does this API actually solve in the real world?
• Who should use it and who shouldn’t?
• How does it compare to alternatives when the tradeoffs matter?
• What does adoption look like beyond the first API call?

For open-source and developer-first teams we’ve worked with, this has meant creating use-case landing pages, problem-led content, and comparison pages that surface outside the docs but guide buyers toward them. 

We’ve written landing pages that help developers self-qualify, founders justify decisions internally, and product teams understand integration paths before touching code.

If you look at how we approach high-intent content, API comparison pages, or decision-stage SEO, you’ll notice that we design for clarity. Because for APIs, clarity is what earns trust.

And when trust comes first, adoption follows naturally.

Notable clients: PQAI, Inspire IP, Triangle IP, Datacipher, Athena Security, and others

Pricing: Our partnerships typically range from USD 5,000 to USD 7,500 per month, with project-based work starting at USD 3,500.

2. Kalungi

Kalungi is a B2B SaaS–focused marketing agency that offers a mix of fractional marketing leadership and execution support. Their services span core SaaS marketing functions including positioning, go-to-market planning, SEO, content marketing, ABM, paid media, and HubSpot implementation. 

The agency positions itself as an external marketing team for SaaS companies that have achieved product-market fit and are looking to formalize or scale their marketing function.

Source – Kalungi

Their engagement model is structured around providing ongoing marketing support rather than project-based work. This typically involves strategic oversight through a fractional CMO alongside a delivery team handling campaigns, systems, and reporting. 

Kalungi works across different stages of the funnel and supports companies with longer sales cycles where coordination between marketing, sales, and operations is required.

Notable clients: Patch, PSIgnite, Beezy, Aware360, Trivalence

Pricing: Mid-to-high monthly retainers, typically suited for B2B SaaS teams looking for ongoing strategic leadership combined with execution support.

3. Grow and Convert

Grow and Convert is a content and SEO-focused agency that works primarily with B2B and SaaS companies. Their services cover SEO-driven content, AI search visibility, and paid search, with an execution model that combines content planning, writing, promotion, and reporting. The agency emphasizes tying content performance to lead generation and conversion outcomes rather than traffic volume alone.

Source – Grow and Convert

Their process relies on internal interviews and structured topic selection to support products with technical depth or complex buying considerations. Engagements are typically ongoing and centered around building and maintaining a consistent content engine, with performance measured across organic search, AI-driven discovery, and paid channels.

Notable clients: Smartlook, RainforestQA, HelpSpot, Crazy Egg, User Interviews, ServiceTitan, FastSpring, Clearscope, Avoma, Weglot

Pricing: Grow and Convert does not disclose pricing publicly and generally offers monthly retainers based on services required.

4. Siege Media

Siege Media is an organic growth agency that focuses on SEO, content marketing, digital PR, and design-led content production. Their work spans industries such as SaaS, fintech, e-commerce, and health, with services covering product-focused SEO, content strategy, generative engine optimization, link building, and digital PR. 

The agency operates with an emphasis on search data analysis to identify ranking opportunities and align content creation with measurable organic outcomes.

Source – Siege Media

Their engagement model is centered on ongoing organic growth programs rather than isolated campaigns. This includes content planning, creation, promotion, and performance tracking across traditional search and AI-driven discovery surfaces. 

Siege Media also supports brands with complementary services like web design and content localization, where organic visibility and consistency across markets are required.

Notable clients: Instacart, Zendesk, Zapier, The Zebra, Mentimeter

Pricing: Siege Media does not publish pricing publicly. Services are offered through custom-scoped monthly retainers based on the scope of SEO, content, and digital PR support required.

5. Directive Consulting

Directive is a B2B-focused marketing agency working with technology and infrastructure-led companies across both mid-market and enterprise segments. Their services cover content marketing, paid acquisition, conversion optimization, go-to-market planning, and revenue operations.

Source – Directive Consulting

Their work typically involves coordinating marketing strategy with data, systems, and execution across channels, especially in environments where multiple stakeholders influence purchase decisions. 

Directive often engages with companies that require tighter alignment between marketing activity and downstream business outcomes, including pipeline contribution and sales performance.

Notable clients: Uber Freight, Snap Inc., Calendly, Adobe, Cisco, Samsung, SentinelOne, ZoomInfo, Redis

Pricing: Directive’s pricing is not listed publicly, and teams are required to speak with their sales group to receive a proposal based on scope, scale, and service requirements.

6. Refine Labs

Refine Labs is a B2B SaaS–focused marketing agency that works with mid-market and enterprise companies. Their services include demand generation strategy, content and creative support, paid media management, and performance measurement. 

Source – Refine Labs

The agency positions its work around updating marketing approaches to reflect current buyer behavior rather than traditional lead-based models.

Engagements typically involve collaboration with in-house teams to review measurement frameworks, plan demand programs, and manage paid acquisition across multiple channels. 

Notable clients: Clari, Bonterra, Calendly, ZoomInfo, SentinelOne, Microsoft

Pricing: Refine Labs lists pricing for select offerings, with strategy and assessment projects starting at approximately $35,000 and ongoing service engagements beginning at around $20,000 per month.

7. Ironpaper

Ironpaper is a B2B marketing agency that works with companies selling into long or complex sales cycles. Their services cover demand generation, account-based marketing, content development, sales enablement, and B2B website strategy.

Source – Ironpaper

Their work typically focuses on improving how marketing supports buyer education and sales handoffs across the funnel. Engagements often involve aligning messaging, campaigns, and systems to support qualified lead generation and buyer engagement over extended decision timelines. 

Ironpaper also works closely with CRM and marketing automation platforms as part of its execution model.

Notable clients: Goddard Technologies, Sparks Group Recruiting, Fleet Management companies, Technology and Industrial B2B brands

Pricing: Ironpaper does not publish standard pricing, and prospective clients are required to discuss requirements directly with the team to receive a proposal based on scope and objectives.

8. Growth Plays

Growth Plays works with B2B software and developer-focused companies that rely on content as a primary growth channel. Their work is centered around planning and operating long-term content programs, covering areas like topic mapping, editorial systems, and performance tracking across search, social, and AI discovery surfaces.

Source – Growth Plays

Rather than operating as a high-volume content shop, Growth Plays tends to focus on how content supports go-to-market priorities over time. Engagements often involve close collaboration with internal teams to connect content decisions with pipeline signals, buyer intent, and revenue attribution.

Notable clients: Lattice, Cortex, Gremlin, Calendly, LaunchDarkly, AlphaSense, Mode Analytics

Pricing: Growth Plays does not list pricing on its website and typically defines commercial terms after an initial discussion.

9. Walker Sands

Walker Sands is a B2B marketing and public relations agency that works with companies across technology, manufacturing, healthcare, professional services, and logistics. Their capabilities span brand and go-to-market strategy, strategic communications, content development, digital marketing, and paid media.

Source – Walker Sands

Their operating model is built around outcome-based marketing, where programs are shaped by defined business objectives rather than isolated channel performance. 

Engagements commonly involve research, messaging development, campaign execution, and reputation management, particularly for organizations navigating competitive categories or multi-stakeholder buying environments.

Notable clients: Sophos, commercetools, Ensono, Paylocity, Semrush, SoftwareONE, John Deere, e2open

Pricing: Walker Sands does not disclose pricing publicly, and commercial terms are determined through direct discussions.

10. The MX Group

The MX Group operates as a B2B-focused agency working with brands that sell into layered, relationship-driven markets. Their work spans areas such as brand definition, go-to-market planning, ABM programs, content execution, digital experiences, and media. Rather than treating these as standalone services, MX tends to approach them as interconnected parts of a broader market presence.

Source – The MX Group

They are often involved when companies need consistency across how they present themselves, generate demand, and support buyer engagement over time. This includes aligning brand narratives with sales motions, managing content across channels, and supporting measurement frameworks that extend beyond short-term campaign results.

Notable clients: SoftwareONE, e2open, Sensitech, KUKA, Ensono, Paylocity

Pricing: The MX Group does not publish pricing details, and commercial terms are typically defined after evaluating the scope of work.

How We Put This List Together

A quick note before you scroll: this list wasn’t built by skimming agency homepages or recycling other roundups.

We looked at these agencies the same way an API-first founder or product leader would evaluate a partner.

Here’s what actually mattered to us:

• Proof of working with complex products: Agencies that have experience beyond UI-led SaaS and can handle technical, behind-the-scenes offerings.
• Ability to translate, not simplify: We prioritized teams that help buyers understand tradeoffs, use cases, and fit, without dumbing things down.
• Decision-stage thinking: Strong signals around comparison content, positioning, and pipeline impact, not just awareness metrics.
• Execution depth, not buzzwords: Clear evidence of structured processes, repeatable systems, and measurable outcomes.

The goal wasn’t to crown the loudest agencies. It was to highlight the ones that actually understand how hard it is to market something that doesn’t want to be seen.

5 Common Marketing Mistakes API-First Companies Keep Making

We see these patterns again and again. Not because teams are careless, but because APIs don’t come with a playbook for marketing.

• Letting the docs do all the talking: Documentation explains how the API works, not why someone should choose it. When docs become the only narrative, buyers miss the context they need to make a decision.
• Assuming developers are the only audience: Developers matter, but they’re rarely the only voice in the room. Product managers, founders, and security teams influence the final call, and they need a different kind of clarity.
• Talking features instead of situations: Endpoints, SDKs, and performance stats don’t answer real questions. Buyers want to know when your API fits, when it doesn’t, and what problem it removes from their workflow.
• Avoiding comparisons altogether: Many API companies stay away from comparison pages, hoping the product speaks for itself. In reality, buyers are already comparing you, just without your input.
• Treating visibility as an afterthought: If your API doesn’t show up where decisions start, search, AI tools, or community research, you’re invisible long before sales gets involved.

These mistakes are common. The good news is, they’re fixable once you stop treating an API like a hidden feature and start treating it like a product that needs context.

If You’re Doing This In-House, Start Here

If you’re handling marketing internally, these are a few places worth focusing on. Nothing drastic. Just small shifts that tend to make a big difference for API-first teams.

• Create a layer before the docs: A simple page that explains when your API is the right choice, who it’s built for, and what problem it removes often helps buyers orient themselves before they dive into documentation.
• Look at where decisions actually start: Check search results, AI tools, and community discussions around your category. If your API isn’t showing up there, it’s a sign that your positioning and content need clearer signals.
• Be open about comparisons: Buyers are already weighing you against alternatives. Walking them through tradeoffs calmly and honestly helps them self-qualify and builds trust early.
• Shift attention from traffic to clarity: Instead of asking how many people visited a page, ask whether the page helped someone understand if your API fits their use case.
• Notice what content supports real decisions: Over time, patterns emerge. Use those signals to guide what you write next, rather than guessing.

All of this is doable on your own, but when clarity, timing, and trust really matter, working with a team like Concurate can help you move faster.

Why API-First Teams Choose Concurate

At Concurate, we don’t assume your API needs more awareness. Most API-first teams we work with already have traffic, docs, and early adoption. What they’re missing is decision clarity.

We’ve seen this firsthand while working with open-source and API-led products where users could access the API easily, but still struggled to understand when to use it, how it compared to alternatives, or how it fit into real workflows. 

In one such project, instead of touching the docs, we built use-case landing pages and decision-stage content that sat before integration and helped the right users self-qualify. You can see how that played out and doubled the number of leads.

That’s the Concurate approach. We don’t market APIs like features. We market them like decisions.

If you want to make your API easier to choose, book time on our calendar, and let’s talk through it.

Frequently Asked Questions

1. Why is marketing an API-first product different from marketing traditional B2B SaaS?

API-first products don’t have a visible interface to demonstrate value. Buyers rely on context, use cases, and trust before integration. Unlike UI-led SaaS, APIs are evaluated by developers, product teams, and founders together, which makes clarity, positioning, and decision-stage content far more important than feature-led promotion.

2. Do API-first companies really need marketing beyond documentation?

Yes. Documentation explains how an API works, but it doesn’t explain why someone should choose it. Marketing fills the gap before the docs by clarifying use cases, tradeoffs, and real-world scenarios. Without this layer, many potential buyers drop off before they ever attempt an integration.

3. What kind of content works best for API-first companies?

The most effective content focuses on problems, use cases, comparisons, and implementation scenarios. Pages that explain when an API is the right choice, how it compares to alternatives, and how teams use it in real environments tend to perform better than generic blogs or feature announcements.

4. How do API-first companies improve visibility in search and AI tools?

Visibility improves when content clearly signals what the API does, who it’s for, and how it’s used. Use-case pages, comparison content, and decision-stage resources help search engines and AI tools surface the API in relevant contexts, especially when users are actively evaluating solutions rather than learning concepts.