Payments · Backend · AI · Cybersecurity
Backend and payment engineering for fintech and SaaS teams.
Consultations, expert reviews, audits and implementation.
Services & starting prices / USD
Choose a consultation, expert review or audit when you need technical judgment. Choose implementation when you need a change built and tested.
Commission expert input without starting an implementation project. Choose the format by the question you need answered.
90-MINUTE PACKAGE
$400
Which option should the team choose?
An agreed short pre-read, a 90-minute working session and a written decision note.
Scope & details ↗ONE AGREED ARTIFACT
From $400
What needs changing in this proposal or code?
Up to three hours in total for a focused review, written feedback and a 30-minute walkthrough.
Scope & details ↗ONE SYSTEM QUESTION
From $400
What is happening in this workflow, and why?
Up to four hours of analysis of one agreed area, with a written assessment.
Scope & details ↗The free 30-minute discovery call is for fit and scope. Paid work starts after the brief, price and timing are agreed. Larger reviews, implementation and recurring advisory support are quoted separately.
When to bring us in
A defect keeps returning, a release has a specific risk or your team needs a second opinion on unfamiliar code.
How the work happens
What you receive
A written assessment with source references, prioritised findings and recommended changes. Each proposed fix includes a way to check it.
Up to four hours of analysis of one agreed area. Implementation, broader testing and retests are quoted separately.
Sample report · realistic engineering scenario.
When to bring us in
Add a PSP, stop duplicate callback effects or resolve a checkout, deposit or payout that gets stuck between internal and provider states.
How the work happens
What you receive
The agreed integration or fix, tests, configuration notes and instructions for investigating failed or unresolved transactions.
One agreed provider or workflow. Provider onboarding, production credentials, compliance decisions and third-party fees stay within the agreed responsibilities.
Sample report · realistic engineering scenario.
When to bring us in
An endpoint is slow, a background job stops progressing or a new feature needs changes across the API, database and workers.
How the work happens
What you receive
A pull or merge request, test results and any required migration, configuration and release instructions.
A defined task, integration or bottleneck. Wider refactoring, infrastructure changes and ongoing support are scoped separately.
Sample report · realistic engineering scenario.
When to bring us in
Connect an assistant to project documents, prepare a code-review brief or extract data from documents. Test one workflow before expanding it.
How the work happens
What you receive
A working pilot, a reusable test set with recorded results, access rules and operating instructions. The handover explains what is ready to use and what needs more work.
One workflow, with model and infrastructure usage billed separately where applicable. Sensitive material is shared with AI providers only under agreed data-handling requirements.
Sample report · realistic engineering scenario.
When to bring us in
Review a sensitive API or login change, check tenant isolation or investigate a suspected application weakness.
How the work happens
What you receive
Findings with reproduction steps, affected code paths, impact assumptions and recommended fixes and retest checks.
Testing is limited to authorised systems and agreed scope. Fix implementation, retests, formal certification and ongoing monitoring are separate engagements.
Sample report · realistic engineering scenario.
Agree the scope before work begins.
The $400 entry audit covers one agreed area. Implementation, broader testing and retests are quoted separately.
Starting prices cover limited engagements. Final deliverables, milestones, timing, taxes where applicable and third-party costs are confirmed in your proposal.
Product delivery & technical decisions
For work across several components, agree a product milestone or compare the architecture options before implementation starts.
How engagements run
Choose the affected system, deliverables and acceptance checks. Agree access and confidentiality before sharing sensitive material.
Review findings or code at agreed milestones. Resolve blockers and approve any change to the scope before adding work.
Receive the code or report, test results and release instructions, with outstanding checks clearly listed.
A consultation works through one decision with your team. A review examines a specific change, design or contract you already have. An audit investigates a system problem using code and available evidence. Each format has an agreed scope and written output.
No. The free 30-minute call establishes fit and scope. The paid consultation includes preparation, a 90-minute working session and a written decision note. Scope, price and scheduling are confirmed before paid work starts.
The entry audit covers one agreed component or workflow, up to four hours of analysis and a concise written report with evidence, prioritised risks and recommended next steps. Implementation, wider testing and retests are scoped separately.
Provider integrations, webhooks, payment states, duplicate processing, reconciliation, APIs and service integrations. Backend work focuses on Go and PHP/Laravel, with scope and verification agreed before implementation.
No. Work can include product assistants, document extraction, internal tools, code review or QA. Choose one task, connect the relevant sources and test whether the output is useful and safe to use.
Access, confidentiality requirements and tools are agreed before sensitive material is shared. Access is limited to the agreed scope. Client names, code and project details are not published without permission.
Book a free 30-minute discovery call or send a brief. Share the affected system, the problem, timing and desired outcome. Price, deliverables and milestones are agreed before work begins.
How we work
Upserto works on backend systems, payment integrations, AI workflows and application security. Experience in fintech and iGaming informs how the work handles transaction states, retries, permissions and recovery.
The work starts with the problem your team needs to solve. The proposal sets the deliverables, price and acceptance checks. Findings and code are shared for review before the agreed handover.
Access is limited to the systems and data needed for the agreed work. Client names, code and project details are not published without permission.
Confidentiality requirements, tools and any sharing with external providers are agreed before sensitive material is used.
Discuss your system ↗Optional Google Analytics helps us understand page visits and whether visitors use contact or booking options. It loads only after you allow analytics. Names, email addresses and project briefs are not included in analytics events. You can change your choice using Analytics settings in the footer.
Identify the affected workflow, required access, useful evidence and a clear definition of done. Confirm the price and deliverables before starting.
Review the relevant findings or code changes at agreed milestones. Test the expected behaviour and failure cases, and list any checks that could not be completed.
Receive the agreed code or report, test results and instructions for release, recovery or follow-up work.
Start a conversation
Describe the system, the problem and the result you need, along with your timeline. A product or public repository link is useful. Private access can follow after scope and confidentiality are agreed.
Use a free 30-minute call to explain the task, ask questions and decide what the first piece of work should cover.
Choose an available time in your timezone. Prefer email? Use the enquiry form.Expert Code & Architecture Review
An independent review of one merge request, API contract, payment flow or architecture proposal. Upserto reads the agreed material and returns specific comments, trade-offs and questions your team can act on. The review can be commissioned on its own, without an implementation project.
See the project brief, proposed solution and acceptance checks for work around a public product.
Read Formbricks integration audit: example scope ↗Public-product reference · proposed delivery plan.Engineering teams and technical founders who already have a change or proposal and want an experienced external reviewer.
Send a short brief and identify the merge request, contract or diagram. Confirm the revision, relevant context and expected behavior. The starting package covers one small agreed artifact, not an entire repository.
Read the affected code and supplied tests or compare the proposal with its stated constraints. Check the relevant interfaces, ownership rules, retries, permissions and operating assumptions. Each concern points to the supplied material.
Receive an annotated diff or written review with priorities, proposed changes and open questions. A 30-minute walkthrough is included within the agreed review time. Your team decides how to address the comments and whether the change is ready to release.
A review gives a second opinion on material you already have: a change, design or contract. An audit investigates a specific system problem using code, configuration and available evidence. If a review uncovers a question that needs reproduction or broader access, Upserto proposes that investigation separately.