About arcitools

arcitools.com is an independently-run collection of free online calculators and utilities for Filipino consumers. The mission is small and concrete: take the everyday money decisions Filipinos already make on the back of a napkin — should I buy this car, will solar pay back, which credit card actually fits my income, what's my real take-home — and turn them into honest, editable, browser-only tools where every assumption is visible.

The site launched in early 2026 from Quezon City. It is run by one person, funded by ads and occasional partner referrals (always labeled), and built in the open on GitHub.

Why this exists

Most Filipino "calculators" online are either US tools with the labels swapped, lead-generation funnels for one bank or insurer, or quick blog posts whose math you can't audit. We kept opening Excel anyway — to compare two car loans, to model a solar install, to figure out whether the 8% optional tax or graduated rates won for a given freelance year. Spreadsheets were always someone else's assumptions buried in someone else's formulas.

arcitools is what those spreadsheets should have been: a public page, every input visible, every default editable, the math explained underneath, and no signup between you and the answer.

What makes a tool different here

• Local by default. Defaults use Philippine prices, tax brackets, contribution tables, fuel rates, and market data. A net-pay calculator has SSS / PhilHealth / Pag-IBIG built in, not bolted on; a vehicle TCO uses DOE weekly oil monitors, not US averages.
• Every number is editable. No "calculate" button hiding the assumptions. Tap any default — fuel price, interest rate, depreciation curve, dividend rate — change it, watch the answer move. If you disagree with our defaults, override them.
• Fast and private. Every calculation runs in your browser. Your salary, your debt totals, your payslip PDFs, the images you process — none of it is uploaded. There is no account, no login, and nothing about your inputs is logged or sold.
• Free, and staying free. No paywalls, no "pro" tier, no email gate. Ads pay the hosting bill so the tools can stay free and get updated.

How we build a tool

A new tool starts as a problem we (or a reader) actually hit. The build pass usually goes: research the underlying rules (tax code, regulator schedule, manufacturer pricing); model the math in code with every constant called out; ship a draft UI with sensible PH defaults; pressure- test edge cases (zeros, negatives, the boundary values where tax brackets jump); write the "How it works" explainer; document sources; review with a fresh eye a day later, then publish.

Each tool page carries a Last reviewed date below the calculator. When rules change — a new BIR bracket, a new MP2 dividend, an updated SSS schedule, a Meralco rate move — we re-run the math, update the defaults, and bump that date. Tools we haven't reviewed recently are flagged so you know to double-check.

Where the numbers come from

We rely on first-party Philippine sources wherever possible: the Bureau of Internal Revenue (income tax, percentage tax, withholding); SSS, PhilHealth, and Pag-IBIG contribution tables; the Department of Energy weekly oil price monitor; Meralco's residential tariff schedule and BSP inflation forecasts; LTO and LTFRB fee schedules; PSE and PDS price feeds; published pricing from Toyota Philippines, BYD, Honda, Mitsubishi, Mazda, Geely, Ford, and the EV importers; rates published by digital banks, telcos, and remittance operators on their own pages. Where third-party aggregators are used (e.g., for fuel-economy estimates), the source is named on the page.

Corrections policy

Numbers go stale. Rates change. We make mistakes. If something looks off — a rate, a fee, a formula — please flag it via the contact page with a source link. Confirmed corrections are usually patched within 1–3 business days and the Last reviewed date is updated. Material corrections get a one-line changelog note on the tool page.

How we make money

Two sources, in this order: Google AdSense display ads, and partner / referral links on tool pages where a relevant partner exists (credit cards, insurance, brokers, etc.). Every partner link is labeled Partner / issuer link below the button. We do not accept paid placement inside the calculator math itself — defaults, rankings, and recommendations are independent of whether a partner pays a referral.

What we don't do

• We don't sell or share your inputs. There's nothing to sell — the math runs in your browser.
• We don't offer financial, legal, or tax advice. The tools are informational. Verify important decisions independently.
• We don't do paid consulting, custom-calculator builds, or sponsored articles.

Who runs this

arcitools is built and maintained by Joseph Arcillas, a software engineer based in Quezon City, Metro Manila. The full code, including every calculation, is public on GitHub. If you want to argue with a formula, the source is right there.

Questions, corrections, partnership inquiries — all go through the contact page.