Tiingo vs Polygon.io: Market Data APIs for Indie Quant Projects in 2026

You are building a backtester, a screener, or a dividend tracker on a weekend budget, and you have hit the question every indie quant hits eventually: where does the data come from? Two names show up again and again for people who refuse to pay Bloomberg-terminal money — Tiingo and Polygon.io. They overlap enough to look interchangeable in a feature grid and differ enough that picking the wrong one means rewriting your data layer three weekends from now.

We pulled both APIs into a small test harness — a Python script fetching daily bars, a few intraday requests, and a fundamentals call — to see where the friction actually lives. What follows is the decision the way a solo builder has to make it, not the way a sales page frames it.

What you are actually choosing between

Tiingo started as an end-of-day (EOD) data shop and still leans that way. Its core strength is clean daily price history going back decades, survivorship-bias-adjusted, plus fundamentals, a curated news feed, crypto, and forex. Intraday equity data comes through IEX, which means you are seeing IEX’s slice of the tape rather than the full consolidated SIP feed. For daily-bar backtests, dividend analysis, and long-horizon research, that distinction does not matter. For anything claiming to model real fills, it matters a lot.

Polygon.io is built around the tape itself. You get aggregates (minute and daily bars), but also trades and quotes — the tick-level data that Tiingo simply does not sell at the indie tier. Polygon covers stocks, options, indices, forex, and crypto, with full historical depth on paid plans and WebSocket streaming for live data. If your project touches options, or you want minute bars you can trust for intraday logic, Polygon is the one with the raw material.

The shorthand: Tiingo is a research-grade EOD and fundamentals provider that happens to offer some intraday. Polygon is a market-microstructure provider that happens to offer daily bars. Most indie projects only need one side of that, and knowing which side you are on settles half the decision before you compare a single price.

Pricing and rate limits on a solo budget

This is where the two diverge hardest, so verify the current numbers before you commit — both vendors revise tiers, and the figures below are directional, not contractual.

Tiingo’s appeal has always been how little it costs. The free tier covers EOD data with modest hourly and daily request caps, enough to prototype an entire EOD strategy without paying anything. The paid “Power” tier has historically sat near $10 a month and lifts those caps substantially — genuinely unusual pricing for adjusted historical equity data, and the main reason hobbyists keep recommending it.

Polygon’s free tier is real but tighter for active development: a low per-minute call ceiling and limited historical lookback that you will outgrow the moment you start backfilling. Paid plans begin around $29 a month for the entry stock tier and climb from there as you add real-time access, more history, and higher rate limits. Options and full tick data live on the higher tiers. The pattern is clear — Polygon costs more because it is selling more granular data, not because it is gouging.

Which one fits your project

Match the API to what you are building rather than to which feature list looks longer.

Pick Tiingo if your project is EOD-shaped: a daily-rebalanced portfolio backtester, a factor screener, a dividend or fundamentals dashboard, or anything where you pull data once a day after the close. The price-to-value ratio is hard to beat, the adjusted history is clean, and you will not pay for granularity you never query.

Pick Polygon if you need intraday truth: options analytics, minute-bar strategies you intend to take seriously, live dashboards over WebSocket, or research that depends on trades and quotes rather than OHLC summaries. You will pay more, but you are buying data Tiingo does not offer at this tier, so the comparison stops being apples-to-apples.

A quietly common answer is both. Several indie builders run Tiingo for cheap historical EOD and fundamentals while subscribing to Polygon only for the specific intraday or options data a strategy needs. Two thin clients behind one internal data interface costs less than over-buying a single premium plan to cover a use case it was never the cheapest tool for.

Whichever you choose, the part that eats your weekends is not the vendor — it is the glue code: retry logic, rate-limit backoff, schema normalization, and caching so you stop re-fetching the same bars. That is the layer worth writing carefully and letting an AI pair-programmer accelerate.

Build the ingestion layer so swapping providers is a config change, not a rewrite. Then the Tiingo-versus-Polygon decision stops being permanent — you can start cheap on Tiingo and graft Polygon in later exactly where the data demands it.