When a founder asks me whether to hire a Sanity developer directly or go through an agency, I never give the same answer twice. The right choice depends almost entirely on where the business is right now — not on which model sounds more professional or costs less on paper. Here are the five trade-offs I walk every client through before they sign anything.

Cost: the number on the invoice is not the whole story

A freelance Sanity developer in a market like India typically runs between $40–80/hour. A mid-tier UK or US agency bills $120–200/hour for the same work, spread across a team where not every hour is a senior hour. On a 200-hour project, that gap is real money.

But cost-per-hour is the wrong unit. The question is cost-per-outcome. Agencies quote fixed-scope projects more reliably because they have PMs, QA, and retainer agreements designed for it. A solo developer quoting fixed scope is absorbing that risk personally — which means scope creep hits you both harder and sooner. If your brief is mature and locked, a freelancer is almost always cheaper for equivalent output. If your brief will evolve for the first three months, the agency overhead starts earning its keep.

One figure worth knowing: a typical Sanity + Next.js marketing site from a mid-tier agency lands between £18,000 and £35,000. A freelancer with equivalent Sanity experience will usually quote £10,000–18,000 for the same scope. The gap narrows on complex projects and widens on small ones.

Speed: who can actually start on Monday

Agencies rarely start on Monday. There is a discovery phase, a contract review, a kick-off meeting, and a sprint-planning session before anyone touches a schema. For a product team that needs a staging URL in two weeks, this is a dealbreaker.

A freelancer with a cleared calendar can ship a working Sanity Studio and basic page templates in days, not weeks. If speed to first preview is a constraint — investor demo, product launch, conference deadline — a freelance Sanity developer almost always wins on raw velocity.

The caveat is bandwidth. A solo developer has one of them. If your project needs simultaneous frontend, CMS configuration, and performance work running in parallel, a single person becomes a bottleneck. Agencies sell parallelism, and on genuinely large scopes that parallelism is worth paying for.

Accountability: who do you call when something breaks

This is the trade-off most founders underestimate. With an agency, there is a named account manager, an SLA, and a company whose reputation depends on returning your call. With a freelancer, you are relying on one person's professional ethic and availability.

That is not a knock on freelancers — the best ones are more accountable than most agencies because the relationship is direct and their referrals depend on it. But it is a risk that scales with project size. On a £5,000 project, a freelancer being unreachable for a day is an inconvenience. On a £40,000 platform, it is a crisis.

If accountability needs to be contractual and escalatable, an agency provides that structure natively. If you are hiring someone you have vetted through referrals and a paid trial, a freelancer's accountability is usually personal and faster to activate.

Post-launch support: retainer vs rehire

Most Sanity projects need ongoing work after launch — new content types, editor training, performance fixes as traffic grows, integrations with new tools. How that gets handled is structurally different between the two models.

Agencies typically offer retainer packages: a fixed monthly fee for a set number of hours, with a response SLA. It is predictable and budgetable. The downside is that you are often billed for hours you did not fully use, and the person doing the work in month six may not be the same person who built the system.

With a freelancer, you re-engage as needed. On a mature Sanity setup, that might mean two or three days a quarter. The cost is lower, but you need the developer to remain available and to remember the context of what they built. Good freelancers document heavily precisely because they know this is how the relationship works. Ask to see documentation samples before you hire.

Risk: what can actually go wrong

With an agency, the main risks are scope inflation, communication layers that slow decisions, and a handoff that leaves your team unable to maintain the CMS without paying the agency for every change. Agencies have commercial incentives to stay in the relationship. That is not always aligned with your incentives.

With a freelancer, the main risks are availability (illness, other clients, life), and the bus-factor problem on a system only one person fully understands. Both are mitigable — escrow, documented schemas, Sanity TypeGen exports, and a handoff checklist go a long way — but they require you to actively manage them.

Neither model is categorically riskier. The risks are just different shapes.

How to pick the right shape for your stage

Here is the heuristic I give founders:

Hire a freelance Sanity developer if your brief is defined, your timeline is tight, your budget is under £20,000, and you have someone internal who can own the relationship day-to-day. Also if you have been referred to a specific person with a portfolio you can verify.

Hire an agency if your project is over £25,000, involves multiple workstreams running in parallel, needs a contractual SLA, or if you have had a bad experience with a solo developer going dark mid-project and cannot absorb that risk again.

Consider a hybrid — a freelance developer for build, an agency for ongoing retainer — if you want the speed and cost of a freelancer for the initial build but the structural accountability of an agency for support. This is more common than people expect and often the best outcome for a growth-stage product team.

The Sanity ecosystem specifically suits the freelancer model well. The CMS is opinionated enough that one experienced developer can configure schemas, GROQ queries, Studio structure, and the Next.js integration without needing a committee. Where agencies earn their fee is on the frontend design system, the QA process, and the post-launch support contract — not on the CMS configuration itself.