SoSoValue

What it is

A free web dashboard for spot crypto ETFs, and the keyed REST API behind it. Most readers arrive for one table: each US spot bitcoin ETF's daily net inflow, cumulative inflow, net assets, premium or discount, sponsor fee and traded value, with an aggregate line across every fund. The API carries the same fields for ether and the other assets that now have US spot funds, and for Hong Kong.

The site's own FAQ defines its "real-time" as a daily update at the start of each ETF trading day, and the ETF page carries the caveat that matters most: issuers disclose at different times, so data a fund has not disclosed on the same day is marked "Not updated". That caveat is the reason a flow total on this site and one somewhere else can disagree until the next morning.

Around the ETF data sits a much wider site: coin prices, house indices, a crypto-stocks section, bitcoin treasury companies, fundraising rounds, macro calendars and an AI-summarised news feed. The same company also runs a decentralised exchange and index tokens. This card covers the data product only.

Pricing

The ETF dashboard is free to read. The website states that in so many words on the ETF page, in a capture from 13 July 2026.

The API key is free too, and the reader applies for it. You open the developer dashboard, submit a form, and wait for the application to be approved before a key appears. The developer page's FAQ, in a capture from 23 August 2025, called the zero-cost tier the "Demo API plan". It said a paid plan would be "launched soon" and sent anyone after higher limits to an email address for a custom enterprise plan. The live developer page could not be read for this card, because the site sits behind a bot wall. So the free and enterprise split comes from that capture, and the numbers come from the current documentation.

Those numbers are 100,000 requests a month and 20 a minute, counted per key. Going over returns a 429 with a retry-after value in seconds. The newer v3 section of the same documentation is less specific: there, the per-minute and per-month quotas "depend on your plan". No page read for this card publishes a second plan or a price for one.

Data & coverage

The ETF module has four endpoints: an aggregate daily summary, a fund list, a per-fund snapshot and a per-fund history. You query the summary by asset and listing country. US covers BTC, ETH, SOL, LTC, HBAR, XRP, DOGE, LINK, AVAX and DOT; Hong Kong covers BTC, ETH and SOL. The two ways to get that wrong return different codes. An unknown symbol is 400003. A real symbol with no listing in that country, such as LTC in Hong Kong, is 400001. All amounts are in US dollars, all timestamps are UTC milliseconds, and weekends and exchange holidays have no rows.

The history window is the constraint that decides whether this is your source. ETF history through the API is limited to the most recent month, on the summary and per-fund endpoints alike. The coin klines are just as short: daily bars only, three months back. A series from the January 2024 launches onward is something the website shows and the API will not return.

The documentation flags three things in the per-fund history that a first client gets wrong:

• The newest row is not settled. Flow and asset figures settle T+1. Today's row arrives with traded value filled in and net_inflow, cum_inflow and net_assets set to null, so data[0] is null for every flow metric. The snapshot endpoint returns the latest settled figures instead.
• volume is not share volume. In the history endpoint it repeats the dollar turnover, as a string. Share volume comes from the snapshot endpoint.
• date is typed inconsistently. The history endpoint returns YYYY-MM-DD strings, while the snapshot's field table types date as a timestamp and its example shows a string.

The documentation's endpoint table gives the ETF endpoints a one-minute update frequency. That is how often the server refreshes, not how often an issuer publishes. The data itself is daily.

A newer v3 API under a separate base URL covers US, Hong Kong and mainland-China equities, listed funds with holdings, and perpetual futures. It lists Binance, Hyperliquid and the vendor's own venue as perp sources and serves quotes, candles and funding snapshots. Its documentation was last updated 29 September 2026. It has a different response contract from v1, and its v3 rate-limit note says no rate-limit headers are returned there.

Integrations

REST and JSON, authenticated by an x-soso-api-key header. A request without a valid key gets HTTP 401 and code 400101, which a check on 4 October 2026 confirmed. The documentation is a GitBook site with an llms.txt, a full-text dump and an OpenAPI 3.0 file covering v1 and v3.

The vendor also ships a terminal client called soso, at version 0.2.0. It can print tables, JSON, CSV or NDJSON, and it has a polling mode and a full-screen dashboard. The docs describe it as a private preview with no public source repository. The useful-links page says TypeScript and Python SDKs and an MCP server are planned. None exists today, which is why the MCP flag above is false.

Limitations

• One month of ETF history through the API. Anything longer means collecting daily from now on, or going to a provider whose history endpoint starts at launch.
• The flow is SoSoValue's number, not the issuer's. An issuer publishes shares outstanding and NAV. A daily flow is derived from them, and SoSoValue does not document the derivation on the pages read for this card.
• Approval-gated key. The key comes after an application is reviewed, not instantly at signup.
• Licence terms not established. The terms page could not be read for this card, so whether the free key allows redistribution, or display in a commercial product, is unknown. Ask before building on it.
• No webhooks or streaming for ETF data. It is a daily series you poll.

Alternatives

CoinGlass API serves bitcoin ETF flow history per ticker from its cheapest paid plan. It also returns shares outstanding and NAV per fund, so a flow can be recomputed instead of trusted. CoinGlass shows the same flow tables free in a browser. For the mechanics behind the number, see how to get spot bitcoin ETF flows as data.