zfin

A financial data library, CLI, and terminal UI written in Zig. Tracks portfolios, analyzes trailing returns, displays options chains, earnings history, and more -- all from the terminal.

Quick start

# Set at least one API key (see "API keys" below)
export TWELVEDATA_API_KEY=your_key

# Build
zig build

# CLI usage
zig build run -- perf VTI           # trailing returns
zig build run -- quote AAPL         # real-time quote
zig build run -- options AAPL       # options chains
zig build run -- earnings MSFT      # earnings history
zig build run -- portfolio          # portfolio summary (reads portfolio.srf)
zig build run -- analysis           # portfolio analysis (reads portfolio.srf + metadata.srf)

# Interactive TUI
zig build run -- i                  # auto-loads portfolio.srf from cwd
zig build run -- i -p portfolio.srf -w watchlist.srf
zig build run -- i -s AAPL          # start with a symbol, no portfolio

Requires Zig 0.15.2 or later.

Data providers

zfin aggregates data from multiple free-tier APIs. Each provider is used for the data it does best, and aggressive caching keeps usage well within free-tier limits.

Provider summary

Data type	Provider	Auth	Free-tier limit	Cache TTL
Daily candles (OHLCV)	TwelveData	TWELVEDATA_API_KEY	8 req/min, 800/day	24 hours
Real-time quotes	TwelveData	TWELVEDATA_API_KEY	8 req/min, 800/day	Never cached
Dividends	Polygon	POLYGON_API_KEY	5 req/min	14 days
Splits	Polygon	POLYGON_API_KEY	5 req/min	14 days
Options chains	CBOE	None required	~30 req/min (self-imposed)	1 hour
Earnings	Finnhub	FINNHUB_API_KEY	60 req/min	30 days*
ETF profiles	Alpha Vantage	ALPHAVANTAGE_API_KEY	25 req/day	30 days

TwelveData

Used for: daily candles and real-time quotes.

• Endpoint: https://api.twelvedata.com/time_series and /quote
• Free tier: 8 API credits per minute, 800 per day. Each symbol in a request costs 1 credit (batch requests do NOT reduce credit cost).
• Candles are fetched with a 10-year + 60-day lookback window for trailing return calculations.
• Returns split-adjusted but NOT dividend-adjusted prices. Total returns are computed separately using Polygon dividend data.
• Quotes are never cached (always a live fetch, ~15 min delay on free tier).

Polygon

Used for: dividend history and stock splits.

• Endpoints: https://api.polygon.io/v3/reference/dividends and /v3/reference/splits
• Free tier: 5 requests per minute, unlimited daily. Full historical dividend/split data.
• Dividend endpoint uses cursor-based pagination (automatically followed).
• Provides dividend type classification (regular, special, supplemental).

CBOE

Used for: options chains.

• Endpoint: https://cdn.cboe.com/api/global/delayed_quotes/options/{SYMBOL}.json
• No API key required. Data is 15-minute delayed during market hours.
• Returns all expirations with full chains including greeks (delta, gamma, theta, vega), bid/ask, volume, open interest, and implied volatility.
• OCC option symbols are parsed to extract expiration, strike, and contract type.

Finnhub

Used for: earnings calendar (historical and upcoming).

• Endpoint: https://finnhub.io/api/v1/calendar/earnings
• Free tier: 60 requests per minute.
• Fetches 5 years back and 1 year forward from today.
• Note: Finnhub requires TLS 1.2. Since Zig's HTTP client only supports TLS 1.3, requests to Finnhub automatically fall back to system curl.

Alpha Vantage

Used for: ETF profiles (expense ratio, holdings, sector weights).

• Endpoint: https://www.alphavantage.co/query?function=ETF_PROFILE
• Free tier: 25 requests per day. Used sparingly -- ETF profiles rarely change.

API keys

Set keys as environment variables or in a .env file (searched in the executable's parent directory, then cwd):

TWELVEDATA_API_KEY=your_key   # Required for candles and quotes
POLYGON_API_KEY=your_key      # Required for dividends/splits (total returns)
FINNHUB_API_KEY=your_key      # Required for earnings data
ALPHAVANTAGE_API_KEY=your_key # Required for ETF profiles

The cache directory defaults to ~/.cache/zfin and can be overridden with ZFIN_CACHE_DIR.

Not all keys are required. Without a key, the corresponding data simply won't be available:

Key	Without it
TWELVEDATA_API_KEY	No candles, quotes, or trailing returns
POLYGON_API_KEY	No dividends -- trailing returns show price-only (no total return)
FINNHUB_API_KEY	No earnings data (tab disabled)
ALPHAVANTAGE_API_KEY	No ETF profiles

CBOE options require no API key.

Caching strategy

Every data fetch follows the same pattern:

1. Check local cache (~/.cache/zfin/{SYMBOL}/{data_type}.srf)
2. If cached file exists and is within TTL -- deserialize and return (no network)
3. Otherwise -- fetch from provider -- serialize to cache -- return

Cache files use SRF (Simple Record Format), a line-oriented key-value format. Freshness is determined by file modification time vs. the TTL for that data type.

Data type	TTL	Rationale
Daily candles	24 hours	Only changes once per trading day
Dividends	14 days	Declared well in advance
Splits	14 days	Rare corporate events
Options	1 hour	Prices change continuously during market hours
Earnings	30 days*	Quarterly events; smart refresh after announcements
ETF profiles	30 days	Holdings/weights change slowly
Quotes	Never cached	Intended for live price checks

* Earnings smart refresh: Even within the 30-day TTL, cached earnings are automatically re-fetched when an earnings date has passed but the cache still has no actual results for it. This ensures results appear promptly after an announcement without wasteful daily polling.

Manual refresh (r / F5 in TUI) invalidates the cache for the current tab's data before re-fetching.

Rate limiting

Each provider has a client-side token-bucket rate limiter that prevents exceeding free-tier limits:

Provider	Rate limit
TwelveData	8/minute
Polygon	5/minute
Finnhub	60/minute
CBOE	30/minute
Alpha Vantage	25/day

The limiter blocks until a token is available, spreading bursts of requests automatically rather than failing with 429 errors.

CLI commands

zfin <command> [args]

Commands:
  perf <SYMBOL>        Trailing returns (1yr/3yr/5yr/10yr, price + total)
  quote <SYMBOL>       Real-time quote
  history <SYMBOL>     Last 30 days price history
  divs <SYMBOL>        Dividend history with TTM yield
  splits <SYMBOL>      Split history
  options <SYMBOL>     Options chains (all expirations)
  earnings <SYMBOL>    Earnings history and upcoming events
  etf <SYMBOL>         ETF profile (expense ratio, holdings, sectors)
  portfolio <FILE>     Portfolio analysis from .srf file
  cache stats          Show cached symbols
  cache clear          Delete all cached data
  interactive, i       Launch interactive TUI
  help                 Show usage

Interactive TUI flags

zfin i [options]

  -p, --portfolio <FILE>   Portfolio file (.srf format)
  -w, --watchlist <FILE>   Watchlist file (default: watchlist.srf if present)
  -s, --symbol <SYMBOL>    Start with a specific symbol
  --default-keys           Print default keybindings config to stdout
  --default-theme          Print default theme config to stdout

If no portfolio or symbol is specified and portfolio.srf exists in the current directory, it is loaded automatically.

Interactive TUI

The TUI has six tabs: Portfolio, Quote, Performance, Options, Earnings, and Analysis.

Tabs

Portfolio -- navigable list of positions with market value, gain/loss, weight, and purchase date. Multi-lot positions can be expanded to show individual lots with per-lot gain/loss, capital gains indicator (ST/LT), and account name.

Quote -- current price, OHLCV, daily change, and a 60-day ASCII chart with recent history table.

Performance -- trailing returns using two methodologies (as-of-date and month-end), matching Morningstar's "Trailing Returns" and "Performance" pages respectively. Shows price-only and total return (with dividend reinvestment) when Polygon data is available. Also shows risk metrics (volatility, Sharpe ratio, max drawdown).

Options -- all expirations in a navigable list. Expand any expiration to see calls and puts inline. Calls and puts sections are independently collapsible. Near-the-money filter limits strikes shown (default +/- 8, adjustable with Ctrl+1-9). ITM strikes are marked with |. Monthly expirations display in normal color, weeklies are dimmed.

Earnings -- historical and upcoming earnings events with EPS estimate/actual, surprise amount and percentage. Future events are dimmed. Tab is disabled for ETFs.

Analysis -- portfolio breakdown by asset class, sector, geographic region, account, and tax type. Uses classification data from metadata.srf and account tax types from accounts.srf. Displays horizontal bar charts with sub-character precision using Unicode block elements.

Keybindings

All keybindings are configurable via ~/.config/zfin/keys.srf. Generate the default config:

zfin i --default-keys > ~/.config/zfin/keys.srf

Default keybindings:

Key	Action
q, Ctrl+c	Quit
r, F5	Refresh current tab (invalidates cache)
R	Reload portfolio from disk (no network)
h, Left, Shift+Tab	Previous tab
l, Right, Tab	Next tab
1-6	Jump to tab
j, Down	Select next row
k, Up	Select previous row
Enter	Expand/collapse (positions, expirations, calls/puts)
s	Select symbol from portfolio for other tabs
/	Enter symbol search
e	Edit portfolio/watchlist in $EDITOR
<	Sort by previous column (portfolio tab)
>	Sort by next column (portfolio tab)
o	Reverse sort direction (portfolio tab)
[	Previous chart timeframe (quote tab)
]	Next chart timeframe (quote tab)
c	Toggle all calls collapsed/expanded (options tab)
p	Toggle all puts collapsed/expanded (options tab)
Ctrl+1-Ctrl+9	Set options near-the-money filter to +/- N strikes
g	Scroll to top
G	Scroll to bottom
Ctrl+d	Half-page down
Ctrl+u	Half-page up
PageDown	Page down
PageUp	Page up
?	Help screen

Mouse: scroll wheel navigates, left-click selects rows and switches tabs, double-click expands/collapses.

Theme

The TUI uses a dark theme inspired by Monokai/opencode. Customize via ~/.config/zfin/theme.srf:

zfin i --default-theme > ~/.config/zfin/theme.srf

Colors are specified as #rrggbb hex values. The theme uses RGB colors (not terminal color indices) to work correctly with transparent terminal backgrounds.

Portfolio format

Portfolios are SRF files with one lot per line. Each lot is a comma-separated list of key::value pairs (numbers use key:num:value).

#!srfv1
# Stocks/ETFs
symbol::VTI,shares:num:100,open_date::2024-01-15,open_price:num:220.50,account::Brokerage
symbol::AAPL,shares:num:50,open_date::2024-03-01,open_price:num:170.00,account::Roth IRA
symbol::AAPL,shares:num:25,open_date::2023-06-15,open_price:num:155.00,account::Roth IRA

# Closed lot (sold)
symbol::AMZN,shares:num:10,open_date::2022-03-15,open_price:num:150.25,close_date::2024-01-15,close_price:num:185.50

# DRIP lots (summarized as ST/LT groups in the UI)
symbol::VTI,shares:num:0.234,open_date::2024-06-15,open_price:num:267.50,drip::true,account::Brokerage

# CUSIP with ticker alias (401k CIT share class)
symbol::02315N600,shares:num:1200,open_date::2022-01-01,open_price:num:140.00,ticker::VTTHX,account::Fidelity 401k,note::VANGUARD TARGET 2035

# Manual price override (for securities without API coverage)
symbol::NON40OR52,shares:num:500,open_date::2023-01-01,open_price:num:155.00,price:num:163.636,price_date::2026-02-27,account::Fidelity 401k,note::CIT SHARE CLASS

# Options
security_type::option,symbol::AAPL 250321C00200000,shares:num:-2,open_date::2025-01-15,open_price:num:12.50,account::Brokerage

# CDs
security_type::cd,symbol::912797KR0,shares:num:10000,open_date::2024-06-01,open_price:num:10000,maturity_date::2025-06-01,rate:num:5.25,account::Brokerage,note::6-Month T-Bill

# Cash
security_type::cash,shares:num:15000,account::Brokerage
security_type::cash,shares:num:5200.50,account::Roth IRA,note::Money market settlement

# Illiquid assets
security_type::illiquid,symbol::HOME,shares:num:450000,open_date::2020-06-01,open_price:num:350000,note::Primary residence (Zillow est.)

# Watchlist (track price only, no position)
security_type::watch,symbol::NVDA
security_type::watch,symbol::TSLA

Lot fields

Field	Type	Required	Description
symbol	string	Yes*	Ticker symbol or CUSIP. *Optional for cash lots.
shares	number	Yes	Number of shares (or face value for cash/CDs)
open_date	string	Yes**	Purchase date (YYYY-MM-DD). **Not required for cash/watch.
open_price	number	Yes**	Purchase price per share. **Not required for cash/watch.
close_date	string	No	Sale date (null = open lot)
close_price	number	No	Sale price per share
security_type	string	No	stock (default), option, cd, cash, illiquid, watch
account	string	No	Account name (e.g. "Roth IRA", "Brokerage")
note	string	No	Descriptive note (shown in cash/CD/illiquid tables)
ticker	string	No	Ticker alias for price fetching (overrides symbol for API calls)
price	number	No	Manual price override (fallback when API has no coverage)
price_date	string	No	Date of the manual price (YYYY-MM-DD, for staleness display)
drip	string	No	true if lot is from dividend reinvestment (summarized as ST/LT groups)
maturity_date	string	No	CD maturity date (YYYY-MM-DD)
rate	number	No	Interest rate for CDs (e.g. 5.25 = 5.25%)

Security types

• stock (default) -- Stocks, ETFs, and mutual funds. Prices are fetched from TwelveData. Positions are aggregated by symbol and shown with gain/loss.
• option -- Option contracts. Shown in a separate "Options" section. Shares can be negative for short positions.
• cd -- Certificates of deposit. Shown sorted by maturity date with rate and face value.
• cash -- Cash, money market, and settlement balances. Shown grouped by account with optional notes.
• illiquid -- Illiquid assets (real estate, vehicles, etc.). Shown in a separate section. Not included in the liquid portfolio total; contributes to Net Worth.
• watch -- Watchlist items. No position, just tracks the price. Shown at the bottom of the portfolio tab.

Price resolution

For stock lots, prices are resolved in this order:

1. Live API -- Latest close from TwelveData cached candles
2. Manual price -- price:: field on the lot (for securities without API coverage, e.g. 401k CIT share classes)
3. Average cost -- Falls back to the position's open_price as a last resort

Manual-priced rows are shown in warning color (yellow) so you know the price may be stale. The price_date:: field helps you track when the price was last updated.

Ticker aliases

Some securities (like 401k CIT share classes) use CUSIPs as identifiers but have a retail equivalent ticker for price fetching. Use ticker:: to specify the API ticker:

symbol::02315N600,ticker::VTTHX,...

The symbol:: is used as the display identifier and for classification lookups. The ticker:: is used for API price fetching. If the CUSIP and retail ticker have different NAVs (common for CIT vs retail fund), use price:: instead.

CUSIP lookup

Use the lookup command to resolve CUSIPs to tickers via OpenFIGI:

zfin lookup 459200101   # -> IWM (iShares Russell 2000 ETF)

DRIP lots

Lots marked with drip::true are summarized as ST (short-term) and LT (long-term) groups in the position detail view, rather than listing every small reinvestment lot individually. The grouping is based on the 1-year capital gains threshold.

Watchlist

Watchlist symbols can be defined as security_type::watch lots in the portfolio file, or in a separate watchlist file (-w flag). They appear at the bottom of the portfolio tab showing the cached price.

Classification metadata (metadata.srf)

The metadata.srf file provides classification data for portfolio analysis. It maps symbols to asset class, sector, and geographic region. Place it in the same directory as the portfolio file.

#!srfv1
# Individual stock: single classification at 100%
symbol::AMZN,sector::Technology,geo::US,asset_class::US Large Cap

# ETF: inherits sector from holdings, but classified by asset class
symbol::VTI,asset_class::US Large Cap,geo::US

# International ETF
symbol::VXUS,asset_class::International Developed,geo::International Developed

# Target date fund: blended allocation (percentages should sum to ~100)
symbol::02315N600,asset_class::US Large Cap,pct:num:55
symbol::02315N600,asset_class::International Developed,pct:num:20
symbol::02315N600,asset_class::Bonds,pct:num:15
symbol::02315N600,asset_class::Emerging Markets,pct:num:10

# BDC / REIT / specialty
symbol::ARCC,sector::Financials,geo::US,asset_class::US Large Cap

Classification fields

Field	Type	Required	Description
symbol	string	Yes	Ticker symbol or CUSIP (must match symbol:: or ticker:: in portfolio)
asset_class	string	No	e.g. "US Large Cap", "Bonds", "Cash & CDs", "Emerging Markets"
sector	string	No	e.g. "Technology", "Healthcare", "Financials"
geo	string	No	e.g. "US", "International Developed", "Emerging Markets"
pct	number	No	Percentage weight for this entry (default 100). Use for blended funds.

For single-asset-class securities (individual stocks, single-focus ETFs), one line at the default 100% is sufficient. For multi-asset-class funds (target date, balanced), add multiple lines for the same symbol with pct:num: values that sum to approximately 100.

Cash and CD lots are automatically classified as "Cash & CDs" without needing metadata entries.

Bootstrapping metadata

Use the enrich command to generate a starting metadata.srf from Alpha Vantage company overview data:

# Enrich an entire portfolio (generates full metadata.srf)
zfin enrich portfolio.srf > metadata.srf

# Enrich a single symbol and append to existing metadata.srf
zfin enrich SCHD >> metadata.srf

When given a file path, it fetches all stock symbols and outputs a complete SRF file with headers. When given a symbol, it outputs just the classification lines (no header), so you can append directly with >>.

Account metadata (accounts.srf)

The accounts.srf file maps account names to tax types for the tax type breakdown in portfolio analysis. Place it in the same directory as the portfolio file.

#!srfv1
account::Brokerage,tax_type::taxable
account::Roth IRA,tax_type::roth
account::Traditional IRA,tax_type::traditional
account::Fidelity 401k,tax_type::traditional
account::HSA,tax_type::hsa

Account fields

Field	Type	Required	Description
account	string	Yes	Account name (must match account:: in portfolio lots exactly)
tax_type	string	Yes	Tax classification (see below)

Tax types

Value	Display label
taxable	Taxable
roth	Roth (Post-Tax)
traditional	Traditional (Pre-Tax)
hsa	HSA (Triple Tax-Free)
(other)	Shown as-is

Accounts not listed in accounts.srf appear as "Unknown" in the tax type breakdown.

CLI commands

zfin <command> [args]

Commands:
  perf <SYMBOL>        Trailing returns (1yr/3yr/5yr/10yr, price + total)
  quote <SYMBOL>       Real-time quote with chart
  history <SYMBOL>     Last 30 days price history
  divs <SYMBOL>        Dividend history with TTM yield
  splits <SYMBOL>      Split history
  options <SYMBOL>     Options chains (all expirations)
  earnings <SYMBOL>    Earnings history and upcoming events
  etf <SYMBOL>         ETF profile (expense ratio, holdings, sectors)
  portfolio [FILE]     Portfolio summary (default: portfolio.srf)
  analysis [FILE]      Portfolio analysis breakdowns (default: portfolio.srf)
  enrich <FILE|SYMBOL>  Generate metadata.srf from Alpha Vantage
  lookup <CUSIP>       CUSIP to ticker lookup via OpenFIGI
  cache stats          Show cached symbols
  cache clear          Delete all cached data
  interactive, i       Launch interactive TUI
  help                 Show usage

Global options:
  --no-color           Disable colored output (also respects NO_COLOR env)

Portfolio options:
  --refresh            Force re-fetch all prices (ignore cache)
  -w, --watchlist <FILE>   Watchlist file

Architecture

src/
  root.zig              Library root, exports all public types
  format.zig            Shared formatters, braille engine, ANSI helpers
  config.zig            Configuration from env vars / .env files
  service.zig           DataService: cache-check -> fetch -> cache -> return
  models/
    candle.zig          OHLCV price bars
    date.zig            Date type with arithmetic, snapping, formatting
    dividend.zig        Dividend records with type classification
    split.zig           Stock splits
    option.zig          Option contracts and chains
    earnings.zig        Earnings events with surprise calculation
    etf_profile.zig     ETF profiles with holdings and sectors
    portfolio.zig       Lots, positions, and portfolio aggregation
    classification.zig  Classification metadata parser
    quote.zig           Real-time quote data
    ticker_info.zig     Security metadata
  providers/
    provider.zig        Type-erased provider interface (vtable)
    twelvedata.zig      TwelveData: candles, quotes
    polygon.zig         Polygon: dividends, splits
    finnhub.zig         Finnhub: earnings
    cboe.zig            CBOE: options chains (no API key)
    alphavantage.zig    Alpha Vantage: ETF profiles, company overview
    openfigi.zig        OpenFIGI: CUSIP to ticker lookup
  analytics/
    indicators.zig      SMA, Bollinger Bands, RSI
    performance.zig     Trailing returns (as-of-date + month-end)
    risk.zig            Volatility, Sharpe, drawdown, portfolio summary
    analysis.zig        Portfolio analysis engine (breakdowns by class/sector/geo/account/tax)
  cache/
    store.zig           SRF file cache with TTL freshness checks
  net/
    http.zig            HTTP client with retries and TLS 1.2 fallback
    rate_limiter.zig    Token-bucket rate limiter
  cli/
    main.zig            CLI entry point and all commands
  tui/
    main.zig            Interactive TUI application
    chart.zig           z2d pixel chart renderer (Kitty graphics)
    keybinds.zig        Configurable keybinding system
    theme.zig           Configurable color theme

Data files (user-managed, in project root):

portfolio.srf           Portfolio lots
metadata.srf            Classification metadata for analysis
accounts.srf            Account to tax type mapping for analysis

Dependencies

Dependency	Source	Purpose
SRF	Local (../../srf)	Cache file format and portfolio/watchlist parsing
libvaxis	Git (v0.5.1)	Terminal UI rendering

Building

zig build              # build the zfin binary
zig build test         # run all tests
zig build run -- <args> # build and run

The compiled binary is at zig-out/bin/zfin.

License

MIT