The system in the middle of your business
Internal tools, operations platforms, and bespoke backends for the work no SaaS quite fits. We model your domain, build the UI your team actually wants, and leave you with code your engineers can read.
tengenx · custom platform
LiveBespoke platform overview
UI · API · Workers · Data · Integrations
Application
Data layer
Workers
Integrations
Tenants
Many
Audit log
Always-on
Test coverage
Pragmatic
20+
Integrations stitched on Promescent ops layer
Multi-tenant
By default, RBAC, audit, scoped data
Open-source
No proprietary lock-in by default
Where this fits
Built for the moments you can't postpone
We don't take work just to take work. This service exists because the problems below are the ones we keep being hired to solve, and the ones we've shipped through more than once.
- You're running the business in spreadsheets that have outgrown their owners
- No SaaS quite fits your workflow, you keep paying for 80% and forking the rest
- Inherited a legacy monolith that nobody wants to touch and everybody depends on
- You need an internal admin so support / ops can stop pinging engineers
- You sell into enterprise and need RBAC, audit log, and SSO yesterday
- Need to integrate 6 systems with consistent state, not 6 brittle Zapier flows
What we ship
Solutions, not slide decks
Each line below is a real deliverable shipped on past engagements, with an honest scope and a metric where it makes sense.
01 / Scope
Internal tools & ops admin
Real, opinionated CRUD: search, bulk actions, role-based permissions, audit log, exportable views, built around the workflows your ops team actually runs.
02 / Scope
Multi-tenant SaaS platforms
Tenants, roles, billing, SSO, audit. The plumbing every B2B SaaS rebuilds badly, done once, properly, with the seams you'll need at scale.
03 / Scope
Custom backends & APIs
Domain-modelled, versioned, OpenAPI-documented. Built so your engineers can extend it without reading our minds.
04 / Scope
Integration & ETL layers
Webhook intake, retry / dead-letter handling, idempotent processors, and a warehouse copy of every important state change.
05 / Scope
Workflow & scheduler
Long-running jobs done right, Temporal or queue-backed workers with retries, observability, and human-in-the-loop checkpoints when it matters.
06 / Scope
Legacy modernisation
Strangler-fig migrations off PHP / Rails / Magento monoliths. Ship value during the migration, not just at the end.
How we work
A delivery rhythm you can forecast
No mystery sprints. Each phase has a real artefact at the end of it, and you'll always know what's coming next.
- 01 Week 0–1
Domain mapping
We model the business in real nouns and verbs before any UI is drawn.
- 02 Week 1
Slice plan
Build / ship plan in vertical slices that each unlock real value on their own.
- 03 Week 2–N
Build
Two-week sprints, demos at the end of each, staging always reachable.
- 04 Pre-launch
Hardening
RBAC, audit log, perf budget, backup / restore drill, on-call setup.
- 05 Launch + 30
Hand-over
Loom + written runbook so your team can extend it the day we leave.
Engagement
Pick the shape that fits, we'll suggest the rest
We don't pretend one engagement model fits everyone. Pick the closest, and we'll right-size on the call.
Industries we ship for
Fixed-scope build
A defined slice, internal admin, integration layer, multi-tenant MVP. Locked scope, vertical slices, demos every two weeks, and code your team can extend.
- Domain model + slice plan
- Build + integrations
- RBAC + audit + observability
- Runbook + handover
Indicative
$60k–$250k
Timeline
10–20 weeks
Embedded engineering pod
A senior pod (2–4) embedded in your delivery rhythm, owning a slice of the platform end-to-end. Sprint cadence, weekly demos, monthly roadmap reviews.
- Roadmap + sprint cadence
- On-call rotation participation
- Code review for in-house team
- Quarterly architecture review
Indicative
From $18k / mo
Timeline
Rolling, 3-month minimum
Architecture audit
Honest audit of the existing system, domain model, dependencies, perf, on-call burden, and a written plan with sequenced wins, not a wish-list.
- Architecture write-up
- Risk register + cost-of-delay
- Sequenced 6-month plan
- Quote-to-execute optional
Indicative
From $7k
Timeline
1–3 weeks
Stack
The tools we reach for
We're not religious about tools, these are the ones we know deeply enough to ship and operate without surprises.
Languages & runtimes
Web frameworks
Data
Workflow & queues
Infra & DX
Common questions
Honest answers, no sales theatre
Will we own the code?
Yes, fully. No proprietary frameworks, no hidden licensing, no source escrow theatre. The repo is in your GitHub org from day one. We work in pull requests reviewed by you, and the day the engagement ends you have everything you need to keep shipping without us.
How do you decide between buying a SaaS and building custom?
If a SaaS gets you 80% there with reasonable seat economics, we'll tell you to buy it. We build custom when the workflow is your competitive advantage, when the integration / data shape doesn't fit any vendor's model, or when SaaS economics break at your volume. The first call is partly that conversation.
Can you migrate a legacy monolith without freezing the business?
Yes, that's the strangler-fig pattern. We stand up the new system alongside the old one, route a slice of traffic / writes to it, prove it under real load, and migrate slice-by-slice. Old system keeps serving until the new one fully owns its surface. We've done this on commerce monoliths and on internal-tool monoliths.
Do you handle infra / DevOps?
Yes, that's part of the build. CI/CD, environments, observability, backups, on-call setup. We'll work inside your existing cloud account (AWS / GCP / Azure / DO) or stand up a new one. The runbook is part of handover, not an upsell.
What happens after launch?
Two paths. (1) You take it in-house, we hand over with documentation and pair on the first month of changes. (2) You retain us as the embedded pod, same team, ongoing roadmap. We do not lock-in via opaque code; the option is yours every month.
Ready when you are
Let's build the system your business actually runs on .
Tell us about the workflow, the people running it today, and where the friction is highest. We'll come back with a domain sketch, a phased build, and a transparent estimate.