Software engineering firmCentral Florida
Built to keep running after the people who built it are gone.
The ordering, pricing, quoting, and scheduling a business runs on — built new, kept running, or replaced. Runbooks, architecture decisions, and access ship with the code, so the next person can run it without us.
Or call (352) 496-2323. If it is not a fit, the answer will say so and say why.
Leadership
TJ Pendarvis, founder · Navy veteran · Twelve-plus years senior full-stack
Entity
Invariant Systems, LLC · Florida LLC · Fully insured, certificate on request
Ownership
You own the code, the data, and the accounts. Transfer does not require our involvement.
Typical project
$5,000 – $50,000. Within two business days, from an engineer.
Current engagement
A federal medical equipment supplier serving VA and DoD facilities. Storefront, a custom contract pricing engine handling federal contract vehicles, and a bidirectional ERP integration. A single production environment where an outage costs revenue the same day. The same engineer since the build began.
Specification
- Entity
- Invariant Systems, LLC · Florida · L26000409255
- Professional liability
- $1,000,000 per claim / $2,000,000 aggregate
- Cyber liability
- $1,000,000 per claim
- General liability
- $1,000,000 per occurrence / $2,000,000 aggregate
- Breach notification
- 48 hours from discovery
- Code, data, accounts
- Client-owned. Transferred on final payment.
- Credential surrender
- 24 hours from termination, certified
- Availability
- 07:00–18:00 Eastern, Monday–Friday
- Proposal turnaround
- 2 business days, from an engineer
- Service level
- Defined per engagement, in writing, before work begins
- Ships with every build
- Runbook · architecture decisions · access manifest · backup and recovery procedure
An invariant is a condition that holds true at every step of a program’s execution.
That is the standard the work is built to.
Services
The work falls into four shapes.
Four kinds of engagement, one standard. Each is scoped in writing before any code is written.
Web application development
Custom applications built around how the work actually gets done, not around a template. Delivered in working increments, so the shape of the thing is visible long before it is finished.
SurfacesReactNext.jsTypeScriptPostgresSupabaseSystems and API integration
Connecting tools, services, and data that were never designed to talk to each other. The goal is that records move reliably and that failures surface loudly instead of quietly.
SurfacesRESTWebhooksERPEDIScheduled jobsQueuesPlatform maintenance and modernization
Keeping working software working as dependencies, traffic, and requirements change underneath it. Aging systems are modernized in place where that is the honest answer, and replaced only where it is not.
SurfacesDependency upgradesData migrationsObservabilityRollback pathsTechnical consulting
Architecture review, feasibility assessment, and a second opinion before a decision becomes expensive to reverse. The deliverable is a written recommendation your team can act on independently.
SurfacesArchitecture reviewFeasibilityWritten recommendation
Named work and references are available on request. They are not published here without asking the client first.
Process
The same four steps, every time.
Intake
You describe the problem. It goes to an engineer, not a form queue, and you get a reply within two business days — either with questions or with a quote. No call is required to get the first answer.
Within two business daysScope
What is included, what is not, and what it costs, written down before any code is. Where an estimate is uncertain, the range is stated instead of padded.
Before any codeBuild
Work arrives in increments you can look at. Nothing goes dark for a month and reappears finished.
Weekly, and visibleHandoff
Runbooks, architecture decisions, and access ship with the last commit. A project is not done when it works, it is done when someone else can run it.
Ships with the code
Approach
The parts that do not change.
Direct collaboration
You talk directly to the engineering side. Nothing is relayed through an account manager, and no context is lost on the way.
Holds at · Every conversation, first to last.
Clear scope, honest estimates
Scope is written down before work starts. When an estimate is uncertain, that gets said plainly rather than padded quietly.
Holds at · Before work starts, and at every change after.
Documentation as delivery
Handoff notes, runbooks, and architecture decisions ship with the code. A project is not done when it works, it is done when someone else can run it.
Holds at · Handoff, and every day after it.
Maintainability over speed
Code is written to be read a year from now, by someone who was not in the original conversation. Short-term velocity that costs long-term clarity is not a trade worth making.
Holds at · Every commit.
The firm
Specifications.
The facts a buyer needs before getting in touch, and where each of them is binding.
- Entity
- Invariant Systems, LLC · Florida limited liability company · Fully insured
- Principal
- Senior full-stack engineering. Twelve-plus years across e-commerce, ERP integration, and custom business systems.
- Domains
- E-commerce platforms · ERP and systems integration · Custom business systems
- Typical range
- $5,000 – $50,000and up. Smaller work is taken when it fits, and it is said plainly when it does not.
- Engagements
- Fixed-fee project · Retainer · Time and materials
- Availability
- Accepting new engagements.
- Location
- Central Florida. Remote worldwide.
- First reply
- Within two business days, either with questions or with a quote.
Where each of these is binding.
| Commitment | What it means | Where it is binding |
|---|---|---|
| First reply | Within two business days, with questions or with a quote. | Policy |
| Estimates | Written before work starts. Uncertainty is stated rather than padded. | In the scope document |
| Price | Scope is written before any code. Work inside that scope is fixed-fee — if it takes longer than estimated, that is not a change order. Work outside it is quoted before it starts. | On a like-for-like written scope |
| Ownership | You own the code, the data, and the accounts. Transfer does not require our involvement. | In the contract |
| Confidentiality | Nothing you provide is used as a reference, a case study, or an example without asking first. | Terms § Your material |
| Analytics | This site runs no analytics, sets no advertising cookies, and shares nothing with third parties for marketing. | Privacy § Short version |
| Insurance | Invariant Systems, LLC is a Florida limited liability company and is fully insured. | Certificate on request |
Where these and a signed contract disagree, the contract wins.
Built for systems that have to keep running.
Invariant Systems is a Central Florida software firm with more than twelve years across e-commerce platforms, ERP integrations, and custom business systems. Veteran-owned, fully insured, working remotely worldwide.
Every engagement is scoped, documented, and handed over so the system keeps running without us. Accounts and repositories are yours from day one, runbooks ship with the code, and work is sized to the outcome rather than to a seat.
Start
If something needs building, or something already built needs to keep working, describe it.
If it is not a fit, the reply will say that and say why. That is a cheaper outcome for both of us than a discovery call.
Or email tj@invariantsys.com — first reply within two business days.