Keeping stock straight across several sales channels is hard. If spreadsheets and a patchwork of tools keep causing oversells, mismatched counts, and the odd panic on a Friday afternoon, you’ve got plenty of company. Most UK businesses on generic inventory software end up reshaping their own processes to fit the software, rather than the other way round.
We build custom multi-channel inventory systems at ByteGears, designed around how your business actually runs. Off-the-shelf tools expect you to change how you work. Ours don’t. We’re a small London consultancy, and we build bespoke systems so you’re not boxed in by a one-size-fits-all platform, and not paying a monthly fee forever to use it.
Most businesses come to us at a clear trigger point: a third or fourth channel goes live and the spreadsheet stops coping, an accountant flags a gap between Shopify stock and the Xero records, a second warehouse opens, or a SaaS renewal lands 30% higher than last year. If any of that sounds familiar, this is the right conversation to be having.
Where off-the-shelf inventory software falls short
For a growing business, a generic inventory tool often adds friction instead of removing it. The complaints we hear are pretty consistent:
- “Real-time” sync that actually batches updates every 15 to 60 minutes, which is exactly the gap an oversell slips through on a busy day.
- You use a fraction of the features and still find gaps where the function you actually need should be.
- Staff burn hours every week on manual workarounds the software forced on them.
- Pricing that scales against you. Per-user seats climb as the team grows; per-order tiers charge you more for selling more.
- Warehouse allocation that only knows “nearest” or “cheapest” and can’t reflect how you actually decide where to ship from.
- Reporting that never quite answers your question, because the report you need isn’t one of the pre-built ones.
- Most platforms are built for the US market, so UK VAT, post-Brexit reverse-charge rules and Making Tax Digital are bolted on rather than native.
- A new channel like TikTok Shop appears and you wait months for the vendor to support it.
Add it up and you’re paying in wasted staff time and lost sales from stock errors, on top of the subscription. And you never own any of it. Your inventory data lives on someone else’s platform, in their format, on their terms.
When SaaS is the right call, and when it isn’t
We won’t sell you a custom build you don’t need. If you’re selling on one to three channels with straightforward fulfilment, a single warehouse, simple Xero or QuickBooks accounting and no unusual rules, a SaaS product is usually the sensible choice. We’re happy to help you pick one, configure it and wire up the integrations.
A bespoke system earns its place when the off-the-shelf approach is genuinely costing you: complex multi-warehouse allocation, channel- or customer-specific pricing rules, approval chains that don’t fit a fixed module, tight integration with a proprietary ERP or legacy system, demand forecasting tied to your own supplier and seasonal patterns, or simply the need to get off per-user and per-order pricing before it caps your growth.
What working with ByteGears looks like
Our UK team builds inventory software that fits how you already work.
We map your workflows first, before any code gets written. Run B2B wholesale, a few retail stores, and three marketplaces at once? That’s the starting point, not an edge case.
You pay once and own the result, code and data included. No SaaS fees stacking up year after year, no per-user penalties as the team grows, and no renewal letter raising the price because the vendor can.
It connects directly to what you’ve already got: Shopify, WooCommerce, Amazon, eBay, your ERP, your accounting software, without paying for middleware to glue it together.
UK specifics come built in: GDPR-compliant data handling, VAT and reverse-charge handling, Making Tax Digital-ready accounting sync, and integrations with UK shipping carriers.
You can add sales channels, warehouses, or product lines later without hitting a wall in the software, or waiting for a vendor’s roadmap.
And support comes from our London team, the people who built it, not an offshore call centre.
Features we typically build in
Every system is shaped around your operation, but most include the following.
- A single dashboard showing live stock levels across every channel and location.
- A single source of truth for available stock, with inventory reserved the moment an order lands so the same unit can’t sell twice.
- Real-time sync to each channel, using webhooks where a marketplace supports them and reliable polling with proper rate-limit handling where it doesn’t.
- Reporting built to answer your questions: sales velocity by channel and SKU, stock turnover, inventory ageing, and margin by channel or supplier.
- Purchase order automation. Set a reorder point and the system raises the PO when stock drops to it.
- Multi-location tracking and allocation across warehouses, shops and third-party logistics providers, with routing rules that reflect how you actually decide.
- Barcode scanning on mobile and desktop for receiving, picking and cycle counts, designed so warehouse staff actually use it instead of reverting to paper.
- Channel-specific rules for pricing, listings, and how stock gets allocated.
- Lot and batch tracking with expiry alerts where traceability matters.
- Role-based permissions and an audit trail of every stock movement and adjustment: what changed, who changed it, and when.
- An API-first build, so it integrates cleanly with the rest of your systems.
How a project runs
We work in four phases.
First, discovery and planning, usually two to four weeks. We document your current processes, where they hurt, what needs to integrate with what, and the state of your existing data, through workshops and a look at your current systems.
Then a data preparation step that’s easy to underestimate. Across most multi-channel businesses, SKU codes, channel mappings and stock counts have drifted apart over years of spreadsheets and separate tools. Cleaning that up before go-live is what stops the new system inheriting the old problems.
Then development, typically twelve to sixteen weeks for a first release. Our UK developers build the system using current frameworks, and you get regular progress updates rather than radio silence. Each marketplace integration is a meaningful chunk of work in its own right, which is why we usually start with your main channel and add the rest in a second phase.
Next, testing, cutover and training. We test it hard, including the integration edge cases, run user acceptance testing with your team, and plan the switch to keep disruption to a minimum. Your team gets trained and you get documentation.
Start to finish, a focused first release is usually three to four months; a broader multi-channel, multi-warehouse system runs longer. We deliver in stages so you have something working early rather than waiting for the whole thing.
What it costs
Custom development costs more upfront than a SaaS subscription. The honest way to compare is total cost over several years, and ownership of the result.
- Three years of mid-market SaaS, once you add setup, per-channel integration work and training, often lands around £20,000 to £40,000. For higher-revenue retailers on growth-priced platforms it climbs well beyond that, and renewals tend to rise each year.
- A custom build is a one-off development cost plus a modest annual maintenance figure. Per-user and per-order pricing disappear, and so do surprise renewal increases.
- No vendor lock-in, no per-user limits, full control over your own code and data.
- You add features and channels when you need them, on your timeline rather than a vendor’s.
Scope drives the number. A focused first release covering one channel and one warehouse is a smaller project; a multi-channel, multi-warehouse system with demand forecasting and complex allocation rules is a substantial one. The free consultation is where we give you a real, scoped figure once we understand your setup, and where we’ll tell you honestly if SaaS would serve you better.
Who this tends to suit
Custom inventory software makes sense for UK businesses where the channel mix has outgrown what a standard tool can handle:
- eCommerce brands managing Shopify, Amazon, eBay and the rest from one place, where overselling and chargebacks have become a real cost.
- Fashion and apparel businesses tracking style, colour and size matrices across hundreds of SKUs, with seasonal swings and high return rates.
- Wholesale and B2B distributors running tiered pricing, customer-specific terms and PO automation across a network of resellers.
- Food and drink suppliers needing lot tracking, expiry alerts and FIFO/FEFO enforcement for traceability and HACCP.
- Manufacturers tracking raw materials, work in progress and finished goods across direct and distributor sales.
- Retail chains keeping physical stores and online sales in sync across multiple sites.
- 3PL providers giving clients live visibility into stock spread across locations.
- Drop-shipping operations syncing supplier stock and tracking margin per supplier across thousands of SKUs.
- Multi-brand sellers and marketplace aggregators needing brand-level stock isolation and per-brand profitability reporting.
The pattern is the same in each case: once a standard tool can’t cope with how complicated your channel mix is, building your own usually ends up the cheaper and calmer way to run.
Common Questions About Custom Multi-channel Inventory Management
How does custom development cost compare to SaaS solutions?
A bespoke build costs more upfront than a monthly subscription, so the honest comparison is total cost over time. Mid-market SaaS plus setup, integrations and training often runs £20,000-£40,000 over three years; for higher-revenue retailers on growth-priced platforms it can be considerably more. A custom system is a larger one-off investment with a modest annual maintenance cost, no per-user or per-order fees, and no surprise renewal increases. It tends to make sense once SaaS limits or escalating costs are actively holding the business back, rather than as a first step.
What's the typical development timeline?
A focused first release covering one main channel, one warehouse, core stock sync and accounting integration usually takes around 12-16 weeks. A mid-market system spanning several channels and locations typically runs 3-6 months, and a large multi-warehouse build with complex allocation rules can take longer. We almost always deliver in phases so you get a working system early rather than waiting for everything at once.
Which sales channels and systems can you integrate with?
We build direct, API-based connections to the channels you actually sell on: Shopify, Amazon, eBay, Etsy, WooCommerce, Magento, BigCommerce and newer marketplaces like TikTok Shop. We also connect accounting (Xero, QuickBooks, Sage), UK couriers (Royal Mail, DPD, Parcelforce, DHL, UPS) and ERP or legacy systems where needed. Where a marketplace supports webhooks we use them for real-time sync; where it doesn't, we build sensible polling with proper error handling and rate-limit awareness.
How do you stop overselling across channels?
Overselling usually happens because stock updates are batched every 15-60 minutes, so the same unit sells twice on two channels in the gap. We hold a single source of truth for available stock, reserve inventory the moment an order lands, and push updates back to every channel as close to real time as each marketplace API allows. We also build conflict handling for the case where two channels claim the last unit at once.
How do you handle updates, support and changes?
The first 12 months of support and minor changes are included. After that you can take an ongoing maintenance and improvement retainer, or run the system in-house using the documentation and code we hand over. Either way you own the code, so you are never blocked from adding a channel or changing a rule. Support comes from the UK team that built the system.
What about data security and UK compliance?
Systems are built with UK GDPR-compliant data handling, role-based access control and audit logging of stock movements and adjustments. We can host on UK infrastructure for data residency, and build in UK VAT handling, post-Brexit reverse-charge rules and Making Tax Digital-ready accounting sync. For food, pharma or other regulated stock we add lot and batch tracking with expiry alerts and full traceability.
When is off-the-shelf software the better choice?
If you sell on one to three channels with straightforward fulfilment, no multi-warehouse routing and standard VAT, a SaaS tool like Cin7, Linnworks or Zoho Inventory is often the sensible option, and we will tell you so. We are happy to help you select, configure and integrate one. A custom build earns its place when SaaS limits, pricing or workflow constraints are genuinely costing you money.