Developer Blog

Technical guides for developers building on the StockFit API. XBRL parsing, point-in-time data, backtesting patterns, and SEC EDGAR engineering notes.

NewAnalysisFinancial Health Score APIAltman Z-ScorePiotroski F-Score

Financial Health Score API: Point-in-Time Data

Get a company's Altman Z-Score and Piotroski F-Score via API, tied to the exact 10-K each score was computed from, not a restated snapshot.

September 5, 202611 min readStockFit Engineering

Product

Pension Funded Status API

Get a company's pension funded status via API: defined benefit plan assets, benefit obligations, and OPEB funding, sourced from the 10-K footnote.

September 4, 202611 min read

AnalysisASC 842 Lease Data APIOperating vs Finance LeaseOff-Balance-Sheet Lease Commitments

Operating vs Finance Lease API: ASC 842 Data

Get a company's ASC 842 lease data via API: right-of-use assets, maturity schedules, and leases signed but not yet begun, cited to the filing.

September 2, 202610 min read

AnalysisRemaining Performance Obligation APIRPO and Backlog DataASC 606 Disclosure API

Remaining Performance Obligation (RPO) API

Get a company's remaining performance obligation via API: SEC-sourced backlog and bookings data, cited to the accession number, not a press release.

September 1, 202611 min readStockFit Engineering

Product

REIT Property Schedule API: Schedule III Data

Get a REIT's per-property Schedule III data via API: cost basis, carrying value, and accumulated depreciation from the 10-K.

August 30, 202611 min read

ProductInstitutional Ownership API13F Position ChangesSEC Form 13F

How to Detect Institutional Buying and Selling

Detect institutional buying and selling from quarter-over-quarter 13F position changes via API, each row citing its SEC accession number.

August 29, 202610 min read

Analysis

Why 13F Filing Data Is Always 45 Days Stale

Why 13F institutional holdings data lags up to 45 days, charted from 8,206 real SEC filings, and how to query it without missing the gap.

August 28, 20269 min read

TutorialAI Economic Model APIAI Hallucination VerificationSEC Filing Citations

AI Economic Model API: Verified Business Thesis

Every claim in StockFit's AI economic model API cites a verbatim SEC filing quote, checked before it ships. See it verified live on Amazon's 10-K.

August 26, 202611 min read

ProductDebt Tranche Structure APICredit Facility Data APISEC Debt Footnote

Debt Tranche Structure API: SEC Filing Data

Get a company's debt tranche maturity schedule, per-tranche coupon rates, and credit facility utilization via API, sourced from the SEC debt footnote.

August 24, 202610 min read

AnalysisBest AI ETFs 2026AI ETF Holdings ComparisonETF Exposure Data

Best AI ETFs in 2026: What to Watch This Year

Best AI ETFs in 2026 ranked by real exposure to Nebius, CoreWeave, Vertiv, and other AI-infrastructure plays, not Nvidia weight alone.

August 24, 202621 min read

Tutorial

How to Analyze ETF Thematic Exposure via API

Analyze ETF thematic exposure via API with sourced industry-group weights and machine-verified prospectus citations, not marketing copy.

August 22, 202610 min read

ComparisonAlpha Vantage AlternativesFundamentals APIAPI Comparison

Alpha Vantage Alternatives: 5 APIs for 2026

Alpha Vantage alternatives compared on price, point-in-time fundamentals, and audit trail: StockFit, EODHD, FMP, Finnhub, and Massive.

August 20, 202612 min read

Tutorial

How to Detect Stock Splits in Historical Data

Detect stock splits in historical data from XBRL ratio tags and share-count cliffs: the corroboration logic behind StockFit's split API.

August 20, 202612 min read

ComparisonInsider Trading APISEC Form 4 APIAPI Comparison

Best Insider Trading APIs in 2026 (7 Compared)

The best insider trading APIs in 2026, compared on Form 4 coverage, cluster-buy signals, and audit trail: StockFit, FMP, Quiver Quantitative, and more.

August 19, 202613 min read

Product

ETF Custodian and Service Provider API

Look up which bank actually custodies an ETF's assets: custodian, administrator, transfer agent, and lending agent from SEC Form N-CEN as JSON.

August 17, 202612 min read

ProductETF Fee Analysis APIETF Expense RatioN-CEN Fee Data

ETF Expense Ratio and Fee API

Compare ETF expense ratios and fees via API: management fee, disclosed waivers, and acquired-fund costs the headline number hides.

August 15, 202612 min read

TutorialS-1 IPO DataSEC EFFECT FilingIPO Calendar API

SEC S-1 IPO Data API: Filing to Effective Date

The SEC S-1 IPO filing data API: registration statement, price-range amendments, and the EFFECT filing that actually marks IPO day, as JSON.

August 13, 20268 min read

TutorialETF Reverse LookupETF Stock ExposureN-PORT

How to Find All ETFs That Hold a Specific Stock

Find all ETFs that hold a specific stock with one reverse lookup API call: ETF stock exposure from SEC N-PORT holdings as JSON, weights included.

July 24, 202612 min read

ComparisonFundamentals APIFinancial Data APIAPI Comparison

Best Fundamentals APIs in 2026 (8 APIs Compared)

The best fundamentals APIs in 2026, compared on free tier, pricing, coverage, and SEC audit trail: StockFit, FMP, EODHD, Alpha Vantage, and more.

July 14, 202614 min read

Product

Accurate Earnings Dates API: Predict and Confirm

How StockFit gets earnings dates right: predict from each issuer's SEC filing cadence, then confirm the next 28 days against Nasdaq-based exchange data.

July 12, 202611 min read

ProductDaily ETF HoldingsETF Holdings APIN-PORT

Daily ETF Holdings: Six File Formats, One API

One daily ETF holdings API across six issuer formats (csv, xlsx, xls, json, html, pdf): 4,900+ funds, point-in-time history, fresher than N-PORT.

June 23, 202612 min read

Analysis

Executive Compensation API: Pay vs Performance

CEO and named-officer pay from SEC DEF 14A proxies as JSON: reported pay vs Compensation Actually Paid, pay-versus-performance, charted across sectors.

June 21, 202612 min read

ProductAlternative DataSEC EDGARQuant Research

SEC EDGAR Alternative Data for Quants

The unconventional alternative data signals hiding in SEC EDGAR: segment operating margins, Compensation Actually Paid, activist 13D filings, fund flows.

June 19, 202613 min readStockFit Engineering

TutorialBeneficial OwnershipSchedule 13D/13GActivist Investors

Beneficial Ownership API: Schedule 13D and 13G

Pull Schedule 13D and 13G beneficial ownership from SEC EDGAR as JSON. Every 5% stake carries its accession number, point-in-time, activist or passive.

June 17, 202612 min read

Analysis

Point-in-Time Data: Essential for Backtesting

How lookahead bias from restated financials, survivorship bias, and reporting lag corrupt backtests, and how point-in-time SEC fundamentals fix them.

June 16, 202611 min read

ReferenceFund TickerCIK to TickerSEC EDGAR

Mapping CIK to Fund Tickers: A Practical Guide

Mapping a fund's CIK to its ticker is brutally hard: the SEC submissions feed carries none, company_tickers_mf.json lags months, and tickers get recycled.

June 16, 202610 min read

Tutorial

Extract EPS and Share Count with Arelle

Extract EPS and weighted-average share count from XBRL with Arelle, plus the as-converted fix for multi-class filers like Visa a naive extractor misses.

June 10, 202612 min read

TutorialRevenue Segmentation APIRevenue by GeographyRevenue by ProductXBRLDimensional FactsSEC EDGAR

Revenue Segmentation API: Geography and Product

Revenue Segmentation API: revenue split by geography and product, period by period, parsed from XBRL dimensional facts in 10-K, 10-Q, and 20-F filings.

June 6, 202612 min read

Comparison

Company Peers API: Accurate Comparable Companies

The Company Peers API returns up to 6 same-industry comparable companies, ranked by revenue and classified by our SFIC system, one call per ticker.

May 29, 202611 min read

TutorialExecutive Officers APIExecutives APICEO dataForm 4Section 16DEF 14ACorporate OfficersSEC API

Executive Officers API: Company Leadership Data

Get a company's current CEO and executive officers, with titles, from the Executive Officers API, built from SEC Form 3/4/5 insider filings.

May 29, 202610 min readStockFit Engineering

Announcement

ChatGPT App for Stock Fundamentals and SEC Data

The StockFit app is live in ChatGPT: ask about earnings, financial statements, insider trades, and ETF holdings, all answered from SEC EDGAR filings.

May 21, 20268 min read

AnalysisFundamental AnalysisStock ValuationInvestment ResearchFinancial StatementsSEC Filings

Fundamental Stock Analysis Explained

How investors use fundamental stock analysis to value companies, screen stocks, and build conviction, plus the financial data inputs behind every step.

May 15, 202610 min read

AnalysisInsider Cluster BuysForm 4Insider TradingS&P 500BacktestingEvent Study

Insider Cluster Buys: What You Need to Know

Does the insider cluster buy signal beat the market? We tested 45 discretionary S&P 500 clusters from 2018 to 2024 against SPY using Form 4 data.

May 13, 202613 min read

TutorialEarnings Calendar APIUpcoming EarningsEPS Estimates

Earnings Calendar API: Developer Guide

The StockFit Earnings Calendar API: upcoming earnings dates, consensus EPS estimates, and report times across US issuers, plus EPS history and 8-K prints.

May 11, 202613 min read

Reference

Understanding SEC Forms: A Guide to 10-K and More

Where the income statement, balance sheet, and cash flow statement live in a Form 10-K, plus 17 more SEC filings that power the StockFit API.

May 9, 202612 min read

ComparisonComparisonFundamentalsAlpha VantageXBRLSEC EDGAR

StockFit vs Alpha Vantage: Fundamentals APIs

StockFit API vs. Alpha Vantage for fundamentals: a side-by-side look at standardized statements, raw XBRL, filings access, insider data, ETFs, and pricing.

May 7, 202613 min read

Tutorial

ETF Analysis: Free-Tier to Forensic

Walk SPY end-to-end with the StockFit fund endpoints: profile, holdings, flows, overlap, fund health, and fee analysis from N-PORT and N-CEN filings.

May 4, 202613 min read

TutorialBacktestingPoint-in-TimeLook-Ahead BiasQuantPIT DataAmendments

Stock Backtesting with the Holy Grail API

Look-ahead bias is the silent killer of quant backtests. StockFit ships a per-fact, per-amendment audit trail, a true point-in-time ledger you can rewind.

April 30, 202613 min read

Comparison

Sector Metrics vs Financial Modeling Prep

Why a single key-metrics shape fails for banks, insurers, and REITs, and how StockFit returns the right metrics for each business model.

April 22, 202614 min read

ComparisonComparisonXBRLSEC APIInsider Trading

StockFit vs sec-api.io: Financial Data APIs

How the two products approach XBRL-to-JSON conversion, insider trading data, and developer ergonomics. Verified facts on both sides, no vendor spin.

April 22, 202612 min read

TutorialXBRLBacktestingSEC EDGARQuant

XBRL Financials to JSON: Guide for Backtesting

Why SEC XBRL is hard to use directly, what "as-reported" really means, and how to assemble a clean point-in-time dataset for systematic strategies.

April 22, 202615 min readStockFit Engineering

Build with the StockFit API

Get your API key and start shipping.