How GrowthSpin Built a Paid Social Agency Operation That Improved ROAS for Justworks

The Client

Justworks is a New York-based HR technology platform founded in 2012 by Isaac Oates. Built as a Professional Employer Organisation (PEO), Justworks helps small and medium-sized businesses manage the full complexity of running a team — combining payroll processing, benefits administration, HR tools, and compliance support in a single, intuitive platform. Its mission is to level the playing field for entrepreneurs: giving smaller companies access to the kind of institutional-grade HR infrastructure and benefits packages that were previously only available to large corporations.

The platform serves thousands of small businesses across the United States, processing over $31 billion in payroll and $8.9 billion in taxes in 2025, and generating over 268,000 W-2s for its PEO customers. Justworks competes in a crowded HR SaaS market alongside Gusto, Rippling, and Deel — differentiating through its high-touch service model, transparent pricing, and the breadth of benefits access it provides to businesses that would otherwise not qualify for enterprise-level packages.

Justworks has raised $143 million across six funding rounds, with a Series E led by Union Square Ventures and FirstMark Capital, and backing from Bain Capital Ventures, Index Ventures, Redpoint Ventures, Spark Capital, and Thrive Capital. The company is valued at approximately $1 billion.

The Challenge

When GrowthSpin began working with Justworks, the marketing team needed more than campaign execution — they needed a systematic, disciplined approach to paid media that they could rely on. In a competitive HR SaaS market where every player is fighting for the same SMB audience across the same channels, operational rigour and reporting clarity are what separate campaigns that compound over time from those that plateau.

Three core problems needed addressing:

• Lack of systematic campaign launch process. Campaigns across Google, Meta, and LinkedIn needed to be set up with consistency and precision. Without a repeatable, structured approach to campaign launch, there was risk of misaligned tracking, inconsistent targeting, and wasted early spend during the critical ramp-up phase.

• Insufficient reporting visibility. The team needed clear, consistent weekly performance reporting across all three paid channels. Without structured reporting, it was difficult to identify what was working, where budget was being wasted, and which optimisation levers to pull — limiting the pace of improvement.

• Multi-channel coordination complexity. Running paid campaigns simultaneously across Google Search, Meta, and LinkedIn requires tight coordination to avoid audience overlap, budget cannibalisation, and conflicting messaging — particularly when targeting the same SMB decision-maker audience across different platforms and intent stages.

Our Approach

GrowthSpin was brought in to build and manage Justworks' paid media operation across Google, Meta, and LinkedIn — acting as a hands-on paid social and search partner responsible for both campaign setup and the ongoing reporting infrastructure that would underpin performance decisions. Our approach centred on three tightly sequenced phases: establishing the right campaign foundations, building a reporting framework that created genuine visibility, and iteratively optimising toward improved return on ad spend.

Phase 1: Systematic Campaign Launch

We began by establishing a structured, repeatable campaign launch process across all three channels. On Google, this meant building campaigns with clearly defined intent stages — from brand and competitor terms through to category and solution-aware searches — ensuring budget was distributed in line with where Justworks' target audience sat in their buying journey. On Meta and LinkedIn, campaigns were segmented by objective and audience, with careful attention to avoiding overlap between platforms that were targeting the same SMB decision-makers. Every campaign was set up with accurate conversion tracking from day one, ensuring the data feeding into platform algorithms was reliable and the reporting baseline was sound.

Phase 2: Weekly Reporting Infrastructure

A consistent weekly reporting cadence was established covering all three paid channels. Reports were built to surface the metrics that mattered most to Justworks' marketing team — ROAS, cost per lead, conversion rates by campaign type, and spend efficiency across Google, Meta, and LinkedIn. Rather than providing raw data dumps, reporting was structured to highlight trends, flag anomalies, and make the optimisation priorities for the following week immediately clear. This gave the internal team the visibility they needed to make informed decisions quickly and created a feedback loop that accelerated the pace of improvement across the account.

Phase 3: Iterative Optimisation Toward ROAS Improvement

With solid campaign foundations and a clear reporting framework in place, the focus shifted to continuous optimisation. Underperforming ad sets were identified through weekly reporting and paused or restructured. Budget was reallocated toward the placements, audiences, and creative formats that were driving the strongest returns on each platform. On LinkedIn, targeting parameters were refined to sharpen focus on HR decision-makers and company founders at SMB-stage businesses — Justworks' core buyer persona. On Meta and Google, creative and bidding strategies were tested and iterated based on the weekly reporting data. The combined effect of this disciplined approach was a measurable improvement in ROAS across the campaign portfolio.

The Results

By combining systematic campaign setup with structured weekly reporting and disciplined iterative optimisation, GrowthSpin delivered a more efficient, better-performing paid media operation for Justworks.

• ROAS improvement across the campaign portfolio — achieved through structured campaign launches, disciplined weekly optimisation, and consistent reallocation of budget toward the highest-performing placements and audiences.

• Full paid media operation live across Google, Meta, and LinkedIn — with campaigns correctly structured by objective, audience, and intent stage from launch.

• Weekly reporting cadence established — giving the Justworks marketing team consistent visibility into ROAS, cost per lead, and spend efficiency across all channels, enabling faster, better-informed optimisation decisions.

• Highly collaborative working relationship — with the internal team citing thoroughness, attention to detail, and ease of collaboration as hallmarks of the engagement.

Key Takeaways

1. Campaign setup is a performance variable, not an admin task. The way campaigns are structured at launch — tracking accuracy, audience segmentation, objective alignment, and intent-stage separation — directly determines how much optimisation headroom you have. Getting the foundations right is not a box-ticking exercise; it is the single most important factor in long-term paid media performance.

2. Reporting is an optimisation tool, not a summary exercise. Structured weekly reporting — built around the metrics that drive decisions, not just vanity numbers — creates a compounding advantage. Each week of clear data makes the next round of optimisation faster and more targeted. Over time, this discipline is what separates campaigns that continuously improve from those that plateau.

3. Multi-channel paid media requires deliberate coordination. Running Google, Meta, and LinkedIn simultaneously for the same audience is powerful — but only when each channel is playing a defined role in the funnel. Without intentional platform differentiation, channels compete with each other rather than compound. Designing the inter-channel strategy as carefully as the individual campaigns is what allows the whole to outperform the sum of its parts.

About GrowthSpin

GrowthSpin is a London-based growth marketing studio led by Neha Divanji. We work as outsourced in-house growth marketers for funded startups and scale-ups, offering fractional growth leadership, performance marketing (Google Ads, Meta, LinkedIn, TikTok), and product strategy with UI/UX design.

Looking for a paid social agency partner to build and scale your multi-channel paid media operation? Book a call at growthspin.co.uk/calendar