Web and AI development
Building it is easy. Building it into a live product isn't.
Features, integrations, and AI shipped into products that already have users. Fixed scope, fixed price, weeks not quarters.
Building software since 2019. Six-year partnerships. Products used by thousands of end users.
Who we work with
Agencies
Your client asked for a feature your team doesn't have capacity for, or asked for AI and your team can prototype it in a day, then spend three months finding out what breaks in production.
We build it properly, under your brand, on your timeline. Your client deals with you throughout. You keep the client relationship and the margin.
SaaS and product teams
You shipped something and it works. Now it needs to survive real traffic, real costs, and in the case of AI, a model that changes underneath you.
We handle the part that comes after the demo.
Founders and businesses
You have a product with real users and a list of things that need building. No in-house team, or one that's already at capacity.
Fixed scope and fixed price on every engagement, so you know what you're getting before it starts.
- JavaScript
- TypeScript
- React
- Next.js
- Vue
- Python
- Node.js
- Docker
- WordPress
- HubSpot
- WooCommerce
- AWS
- JavaScript
- TypeScript
- React
- Next.js
- Vue
- Python
- Node.js
- Docker
- WordPress
- HubSpot
- WooCommerce
- AWS
What breaks AI features in production
A lot of what we get asked for now is AI. It's also where most of the breakage is.
Anyone can get a demo working. These are the five things that surface later, usually in front of your users.
Runaway tool-calling costs
An agent that loops on a tool call turns a $40 month into a $4,000 month. Almost nobody builds a kill switch until after it happens.
No rate limiting or capping
No ceiling on spend, no throttle on abuse, no fallback when the provider starts returning 429s at the worst possible moment.
No evals
Code has tests. AI output usually has nothing. Which means regressions get found by your users instead of your team.
Injection and data exposure
User input reaching the model unsanitised. Keys exposed client side. Customer data landing in logs, or in a provider's training path.
Model drift
Providers deprecate versions and quietly shift behaviour. A feature that worked in March degrades in July, and nobody is watching for it.
We build the version that handles all five.
What we build
Chat and assistants, document processing, search and retrieval, data extraction, workflow automation, plus the web and integration work around them. Built into products that already exist and already have users.
Already shipped something and it's fragile? Cost controls, evals, rate limiting, security hardening, and monitoring for AI features that are already live.
Engineering capacity under your brand, in your tools, on your cadence. Your client never deals with us.
Continuous capacity for feature work, fixes, and client requests. No re-onboarding every project.
Selected work
Four engagements, in production.
The dev team behind a US digital agency
Builds, migrations and integrations across their client portfolio, under their brand. Their clients see one team.
~$1.2M
handled in one evening
WordPress · WooCommerce · PHP · JavaScript · AWS · Payment integrations
Read the case studyAI-powered financial workflow automation
Natural-language requests to formatted analytical output, inside Excel and PowerPoint.
Office.js · Tool calling · Market data
Read moreCalled back to ship menutize.ai's relaunch
Four Stripe flows, a 1,000-domain ceiling, and a deployment move in two days.
Rails · React · Stripe Connect
Read moreDesign files to production templates
Brand guidelines turned into template systems non-designers can actually use.
React · TypeScript · Animation
Read morePricing
Free scope
$0
48-hour turnaround
Send us the brief. You get back a scope, timeline, and a fixed price within 48 hours.
- Scope and deliverables defined
- Fixed timeline
- Fixed price, agreed upfront
- No commitment
Pilot build
$1,500 – $2,500
1–2 weeks
One contained feature from a live project. The low-risk way to see how we work before committing to anything larger.
- Single feature, fixed scope
- Fixed price agreed upfront
- Built under your brand if you want it that way
- Code, documentation, and handover included
Core build
From $5,000
3–6 weeks typical
A full feature or integration, shipped to production. Cost controls, evals, rate limiting, and security hardening included as standard, not as extras.
- Full integration into your existing product
- Production hardening built in from day one
- Fixed scope, fixed price, fixed timeline
- Full documentation and handover
Retained capacity
From $2,800/mo
Month to month
Ongoing build days on your team. Feature work, fixes, and incoming requests without re-onboarding every time.
- Agreed build days per month
- Up to 50% unused days roll over
- Work in your repo and tools
- Month to month, cancel anytime
Every engagement is fixed scope and fixed price. Changes get quoted separately, so nothing moves silently.
Frequently asked questions
Straight answers on fit, scope, and how we work, so you can decide faster with less back-and-forth.
What kind of work do you take on?
Features and integrations built into existing products: web, integrations, and AI. On the AI side that's chat and assistants, document processing, search and retrieval, data extraction, workflow automation. We also harden AI features that are already live but fragile in production.
We're not sure what's realistic. Can you help scope it?
Yes. Send us the brief and you'll get back a scope, timeline, and fixed price within 48 hours. Free, no commitment.
Do you work under our brand?
Yes, when that's what you want. We work in your tools, on your cadence, and your client deals with you throughout. How you present the arrangement is up to you.
How do we start without committing to a full project?
Most people start with a single contained feature from a live project. Fixed price, one to two weeks, so you can see how we work before anything larger.
How long does a feature take?
A contained feature is usually one to two weeks. A full integration into an existing product typically runs three to six weeks depending on scope. You get a fixed timeline before work starts, not an estimate that moves.
What if the scope changes mid-project?
Fixed scope and fixed price means changes get quoted separately rather than absorbed silently or argued about later. You'll always know what a change costs before we build it.
What do we get at handover?
Working code in your repository, documentation, and everything needed for your team to maintain it. No dependency on us unless you want ongoing support.
Can you work with our existing codebase?
Usually yes. We've worked in codebases we didn't write since 2019, including ones that needed rescuing first. If something is beyond repair we'll say so before taking your money.
How do you handle communication?
We integrate into your existing tools: Slack, ClickUp, Asana, Linear, whatever you use. You don't need to learn anything new.
How do I cancel a retainer?
Retainers are month-to-month. Cancel anytime with 14 days notice before your next billing cycle. No lock-ins, no penalties.
What our clients say
Founders, agencies, and product teams across Europe, the US, and beyond. References available when clients allow.
- Agency
Slark Labs has been our go-to dev partner for over a year, delivering across multiple client sites including a campaign that helped our client raise nearly $1.2M at a single event. Fast, reliable, no drama - exactly what you need in an agency partner.
- Agency
Slark Labs understood the brief immediately and delivered a precise solution within the quoted timeline. The fix affected hundreds of our clients who are now very happy. Exactly the kind of reliable dev partner an agency needs.
- SaaS
Slark Labs helped us hit a critical release deadline, shipping new features and fixes without drama. A reliable development partner you can trust to deliver when it matters.
- Business
Slark Labs handled our MarianaTek integrations with precision and professionalism. Communicative, thorough and great quality work - I wouldn't hesitate to work with them again.
- Engineering
Slark Labs are truly full-stack, excelling in both front-end and back-end development. Clear communication throughout, and when faced with difficult challenges they always found a way forward.
- SaaS
Slark Labs delivered exceptional work throughout our engagement. Communication was excellent, and when given feedback they came back with everything addressed. A development partner you can rely on.
- Agency
Slark Labs are great problem solvers, willing to try new approaches and always take client feedback on board to find the right solution.
Tell us what needs building
Send us the brief and you'll get back a scope, timeline, and fixed price. Fifteen minutes, no commitment.