# SigmaDev Digital

> We build websites, online stores, customer portals and business software,
> then host it, watch it and keep it running. Clients anywhere, and everything
> explained in plain language.

## Contact

- Email: info@sigmadev.digital
- Free quote: https://sigmadev.digital/contact/

## Pages

- [Home](https://sigmadev.digital/): what we build, selected work, how an engagement runs, common questions and credentials.
- [What we build](https://sigmadev.digital/services/): every offering in full, plus the engineering behind it.
- [Our work](https://sigmadev.digital/work/): delivered projects, described by industry.
- [Tools](https://sigmadev.digital/tools/): 166 calculators, converters and generators for running a business online.
- [Field notes](https://sigmadev.digital/insights/): longer technical write-ups.
- [Get a free quote](https://sigmadev.digital/contact/): brief intake.
- [Privacy](https://sigmadev.digital/privacy/) and [Terms](https://sigmadev.digital/terms/).

## What we build

- A website that brings in enquiries — fast, mobile-ready, findable, and editable by the client afterwards.
- An online store or booking system — orders, payments and appointments taken online, with stock and receipts handled.
- A customer or staff portal — a private area where customers check their account or a team does its work.
- Custom software — the part off-the-shelf software does not cover, usually starting with one process.
- Joining up existing systems — website, accounting, CRM and payment tools passing information automatically.
- Fixing or taking over an existing system — including ones with no documentation and no original developer.

## How the work is built

- Websites & apps — TypeScript, Node.js, Express, Middy.js, Python, Go, PHP, Laravel and C#.
- Hosting & reliability — AWS and GCP; Terraform, Pulumi and CloudFormation; Docker and Kubernetes; GitLab CI and GitHub Actions; Prometheus, Grafana and CloudWatch.
- Data & automation — PostgreSQL, MySQL, MongoDB, DynamoDB, Aurora, RDS, Firestore and SQLite; scheduled ingestion; orchestration with Dagster; Gemini and OpenAI integration.
- Specialist work — automated phone menus on Amazon Connect and Avaya with regression testing in Cyara; crypto wallet sign-in and payments; Solidity smart contracts.

## Tools

166 tools at https://sigmadev.digital/tools/, searchable and grouped by
category. All but one run entirely in the visitor's browser — nothing is
uploaded, stored or sent to a server, and no sign-up is required.

- Business (18) — VAT and sales tax, profit margin and markup, break-even, loan repayment, compound interest, ROI and payback, CAC and LTV, cash runway and burn, freelance hourly rate, discount and sale price, invoice and quote totals, A/B test significance, churn and retention, salary to hourly, percentages, bill splitting, late payment interest, and what slow pages cost.
- Marketing (15) — AdSense readiness, Google and social preview, campaign link builder, robots.txt, business schema, social and ad character limits, Open Graph and Twitter cards, XML sitemap, hreflang, conversion funnel, canonical and meta robots, email subject line testing, readability, bulk slugs, ad spend and ROAS.
- Developer (17) — JSON formatter and validator, Base64, URL encoding, hashes (MD5, SHA-1, SHA-256, SHA-384, SHA-512), HMAC signatures, UUIDs, password generation, JWT decoding, regular expressions, CSV and JSON conversion both ways, Unix timestamps, number bases, cron explanation, query strings, text to hex and binary, list comparison.
- Text (14) — word and character counting with readability, case conversion, slugs, find and replace with regular expressions, line sorting and deduplication, text comparison, placeholder text, keyword density, Markdown to HTML, HTML to text, HTML entities, whitespace cleaning, text reversal, character frequency.
- Design (9) — colour conversion, WCAG contrast checking, palette generation, CSS gradients, box shadows, aspect ratios, image resizing and conversion, favicon generation, px/rem/em conversion.
- Data (10) — unit conversion, temperature, date differences, age, time zones, statistics, random numbers and picking, Roman numerals, numbers to words, transfer times.
- Web (2) — password strength, HTTP status code reference.

Startup and engineering tools within those categories: LLM API cost per request
and per user including prompt-cache savings, token and context-window
estimation, SaaS metrics (NRR, gross churn, quick ratio, Rule of 40), burn
multiple and capital efficiency, funding-round dilution with option-pool
top-up, equity vesting schedules, usage-based pricing modelling, cohort
retention curves, payment processing fees, cloud cost and egress estimation,
traffic capacity planning by Little's Law, SLO error budgets and burn rate,
database connection pool sizing, time-series and telemetry storage planning,
SOC 2 and GDPR readiness scorecards, cloud workload carbon, and solar payback.

The only tool that uses a server is the AdSense readiness checker, because
reading another website is something a browser cannot do.

## For funded startups

Teams who can already build come to us for a specific gap:

- A first version in weeks, on fixed scope and a fixed price.
- AI features built to an agreed unit cost — retrieval, prompt caching, evaluations, and a cost per request you can put in a pricing model.
- Unblocking enterprise sales: SSO and SAML, audit logging, role-based access, tenant isolation, data residency, retention and deletion that reaches every copy.
- Cutting the cloud bill, with each change costed and its saving verified.
- Getting ready for load: capacity modelled, load-tested, bottlenecks fixed, SLOs and alerting in place.
- A data and telemetry pipeline that validates before it stores and downsamples on a deliberate policy.
- Technical due diligence for investors and boards.
- A senior engineer available for architecture review, hiring support and the decisions that are expensive to get wrong early.
- Software that handles regulated data — health, financial and identity — built to the rules from the first commit, with the evidence an assessor asks for.
- Marketplace and platform engineering: split payments and payouts, escrow, ratings and trust, disputes, and matching that makes both sides clear.
- Backends for devices and fleets: per-device identity, over-the-air updates that roll back, telemetry that survives a bad connection, and an operations console.
- Security engineering: vulnerability management triaged by reachability rather than score, secrets out of the repository, scanning that blocks in CI, and a rehearsed response plan.
- Accessibility that passes a real audit: keyboard operability, correct roles and states, contrast, reflow, and status messages — tested with a screen reader.
- Making deployment boring: tests that run in minutes, small deployments, migrations that roll back, feature flags, and monitoring that tells you before a customer does.
- Turning your data into an API product: versioning, keys and quotas, rate limits, usage metering that matches the invoice, SDKs and documentation.

Sector tools cover HIPAA readiness, marketplace take rate and liquidity,
hardware cost at volume and subsidised-hardware payback, fleet economics,
DAU/MAU and viral coefficient, course funnels, API quota planning, property
yield, inventory turns and cash conversion, food and CPG margin, launch cost
per kilogram, battery range, blockchain transaction cost, R&D milestone
runway, landed cost, support staffing and experiment duration. Engineering and industry tools cover
DORA delivery metrics, WCAG accessibility readiness, vulnerability SLAs and
backlog burn-down, security incident cost, levelised cost of energy, carbon
removal cost per tonne, freight cost per mile, automation and robotics ROI,
billable utilisation, occupancy and RevPAR, construction cost and contingency,
Sharpe and drawdown statistics, queueing and throughput, material recovery,
quantum error-correction overhead, aviation seat-mile cost, clinical trial cost
per patient, warehouse throughput, on-call load, and technical debt interest.

## How an engagement runs

1. A free conversation, about an hour, with an honest answer on whether we are the right people.
2. A written quote in plain language: scope, price, timeline, and what is deliberately left out.
3. We build, with a working link the client can check at any point and a weekly call.
4. Live in the client's own accounts, with written instructions — then either they run it or we do.

## Common questions

- Cost is quoted per project, not from a price list, and always in writing before work starts.
- Most first releases take between two and eight weeks.
- The client owns the code, accounts, domain and hosting.
- Existing systems can be taken over, including undocumented ones.
- Ongoing hosting, updates, backups and monitoring are available for a fixed monthly amount.
- Everything is done remotely; there is no requirement to be in the same country.

## Track record

Client engagements are covered by confidentiality and are described by industry.
Every figure below is from the engagement it refers to.

- Digital advertising — a busy platform moved off shared hosting onto GCP with no downtime, and partner systems given a direct connection.
- Sports prediction — live fixture data collected automatically and validated before saving, feeding a website and a browser add-on.
- Web3 marketplace — crypto wallet sign-in and payments, on AWS defined entirely as code.
- Consulting engagement — publishing an update cut from 30 minutes of manual steps to under 10, a 66% reduction.
- Consulting engagement — supervision that restarts a crashed background process automatically.

Delivery teams have also been led and trained as part of these engagements.

## Credentials

- AWS Certified Solutions Architect – Associate.
- B.Sc Computer Science.

## Field notes

- [Off shared hosting, without a maintenance window](https://sigmadev.digital/insights/off-shared-hosting-without-a-maintenance-window/)
- [Recovery that happens before the pager](https://sigmadev.digital/insights/recovery-before-the-pager/)
- [Crawling a site that does not want to be crawled](https://sigmadev.digital/insights/crawling-a-site-that-does-not-want-it/)

## Machine-readable

- [Sitemap](https://sigmadev.digital/sitemap.xml)
- [Robots](https://sigmadev.digital/robots.txt)