Open source JavaScript utilities behind gratistools.be, focused on Belgian business formats and privacy-first local file processing.
This package contains the reusable local processing logic behind parts of gratistools.be. The website itself, account features, analytics, deployment configuration and operational code are intentionally not part of this repository.
The package now also exposes browser-local building blocks for inspecting and editing Parquet and Delta Lake data:
- read and rewrite Parquet data with explicit types;
- inspect Parquet schema, row groups, column chunks, codecs, encodings, statistics, sizes and key-value metadata;
- replay Delta JSON transaction logs and inspect version-by-version history;
- load an older Delta snapshot without mutating history;
- compare Delta versions;
- append a coherent overwrite commit while preserving the existing log and data files;
- append a RESTORE commit when the referenced historical Parquet files are still present.
The high-level UI lives on GratisTools.be; this repository contains the reusable MIT-licensed logic. Existing Delta log versions are treated as immutable. Low-level Parquet offsets/statistics are inspected read-only and are regenerated on rewrite rather than edited by hand.
import {
readParquetBuffer,
inspectDeltaEntries,
readDeltaEntries,
appendDeltaZip,
restoreDeltaZip,
} from 'belgian-utils'The three GratisTools open-data checkers use src/be/open-data.js, licensed MIT.
The library includes a quoted CSV/TSV parser, safe Belgian number parsing,
source-column detection, cross-checking FAVV operator/PAP/Smiley records,
Statbel property percentiles and comparisons, and NACE sector time-series rows.
Data is not bundled in the npm library. Download current original source files from the FAVV or Statbel. The website supports local file import, including source ZIPs. Keep source date, coverage and suppressed values visible. An absent match in a user's file does not establish that a company is unregistered. The interface and deployment remain part of the separate private Gratistools application.
- Belgian enterprise and VAT number validation
- Belgian IBAN, bank code and BIC helpers
- OGM and RF payment reference helpers
- Belgian national number parsing and synthetic RN/BIS/INSZ test-number generation
- Peppol participant ID parsing
- CODA parsing and anonymisation
- CAMT parsing
- UBL invoice reading and anonymisation
- Peppol BIS validation helpers
- Intervat parsing
- Belgian XBRL parsing and comparison
- Belgian file format detection
- Identifier scanning
- EPC payment QR payload generation
- Lambert 72 and Lambert 2008 conversion
- Shared safe XML and CSV helpers
- Local metadata inspection and privacy cleaning for JPEG, PNG, WebP, DOCX, XLSX and PPTX
- Local PDF page composition: reorder/delete pages, insert pages from another PDF, rotate pages, and add JPG/PNG images as PDF pages\n- Belgian notice-period, indexation, rent, company-car VAA and mobility-budget calculators\n- Belgian VAT-grid reference and enterprise-number batch cleaning\n- 2025 municipality-merger/NIS mappings and 2026–27 school holiday calendars\n- Belgian statutory/commercial interest history and working-day calculations\n- Local XLSX reader + one-to-many NACE-BEL 2008→2025 migration mapping
- Weighted decision matrices with cost/benefit normalization, dominance detection and weight sensitivity analysis
- Reproducible simple, systematic and stratified sampling, including finite-population sample-size planning
- Consensus ranking with Schulze strongest paths, Borda, Copeland, Condorcet checks and pairwise matrices
- Availability interval merging and duration-aware maximum-attendance meeting-window optimization
- ISO 20022
pain.001.001.09SEPA payment batch generation and local validation - Explainable UBL invoice ↔ CODA/CAMT transaction reconciliation
- Peppol/UBL invoice batch auditing for validation counts, duplicates, VAT totals and overdue invoices
- Belgian 2026 LEZ comparison rules for Brussels, Antwerp and Ghent
- Belgian postcode/place → municipality, NIS, region and official service-routing helpers
- Region-aware official property/parcel resource selection for CadGIS, Geopunt, WalOnMap and BruGIS
The reusable engine behind the PDF page editor is exported as composePdfPages. It works entirely on bytes and has no network access:
import { composePdfPages, inspectPdfPages } from './src/index.js';
const info = await inspectPdfPages(mainPdf);
const edited = await composePdfPages({
sources: {
main: { type: 'pdf', bytes: mainPdf },
extra: { type: 'pdf', bytes: extraPdf },
photo: { type: 'jpeg', bytes: jpegBytes },
},
pages: [
{ source: 'main', page: 2 },
{ source: 'photo', pageSize: 'a4', margin: 24 },
{ source: 'extra', page: 1 },
{ source: 'main', page: 1, rotate: 90 },
],
});The order of pages is the output order. Omitting an original page deletes it. Repeating a page duplicates it. JPG and PNG images can become natural-size pages or be fitted onto A4/custom page sizes. The hosted gratistools.be UI adds previews, drag-and-drop and broader image-format conversion around this core.
The analysis engines are UI-independent and operate on ordinary JavaScript arrays and objects. Seeded sampling is deterministic for audit/reproduction; unseeded sampling uses browser cryptographic randomness where available. Availability functions work on timestamps, while the text parser can interpret local browser time (including daylight-saving rules) or a fixed offset.
import {
analyzeDecisionMatrix,
stratifiedSample,
parseBallots,
consensusRank,
bestMeetingWindows,
} from './src/index.js';The decision matrix exposes normalized scores, dominated alternatives and winner stability bands instead of only a final score. Consensus ranking returns the complete pairwise matrix so cycles and method differences stay inspectable.
The finance engines are ordinary JavaScript functions with no network access:
import {
buildPain001,
reconcileInvoices,
auditInvoices,
} from './src/index.js';buildPain001() creates ISO 20022 pain.001.001.09 XML and validates the most important batch inputs such as IBANs, amounts, references and duplicate end-to-end IDs. Bank-specific upload profiles can add stricter rules, so production payment files should still be tested with the target bank.
reconcileInvoices() scores sales invoices against incoming bank transactions using explainable signals: payment reference, exact amount, invoice number, customer name and date proximity. It returns matched, probable/review, unmatched and duplicate-looking records instead of hiding the matching rationale.
auditInvoices() operates on normalized UBL invoice models and their validation issues. It reports duplicate invoice identities/fingerprints, validation counts, VAT totals, overdue items and supplier/customer aggregates.
These engines stay intentionally narrow and explainable:
compareBelgianLez()compares encoded 2026 M1/N1 access thresholds across Brussels, Antwerp and Ghent while returning each city's official checker for exemptions and special cases.findPlacesByPostcode()andauthorityProfile()turn an external Belgian postcode/place dataset into municipality, NIS, region and service-routing output. They do not guess a police zone, water supplier or waste operator when the boundary is more granular than the input.propertyResources()chooses the relevant official federal/regional property portals for an already geocoded point. It does not geocode, identify a legal cadastral parcel, or claim to replace an official certificate.
The hosted gratistools.be interface supplies the current bpost/Statbel place dataset and the browser geocoding UX separately.
The utilities in this repository are designed for local processing. They do not upload files or send data anywhere by themselves.
The hosted website at gratistools.be also offers a small number of explicitly marked online lookups. Those network features are separate from this package.
npm testimport { parseEnterprise, parseIban, parseOgm, makeInsz } from './src/index.js';
console.log(parseEnterprise('BE 0753.124.628'));
console.log(parseIban('BE73 7350 1234 5660'));
console.log(parseOgm('+++202/6000/12320+++'));
console.log(makeInsz({ type: 'national', birthDate: '2099-01-01', sex: 'female', sequence: 2 }));This is a Belgian utility library, not a complete application and not an official government package.
Formats and rules can change. Consumers should verify critical financial, tax or regulatory use against the relevant official source.
A browser-based interface for these and many other tools is available at gratistools.be.
MIT