Free Forex API
Live vs Reference Rates免费外汇 API
实时报价与参考汇率
Daily central-bank rates are ideal for accounting but not trading. Separate reference, indicative, and executable FX data before choosing an API.
央行每日参考汇率适合记账，却不适合交易。选择 API 前应分清参考、指示性和可执行外汇数据。
TL;DR
Frankfurter is open source, requires no key, and exposes daily rates from many central banks with provider filtering.
ExchangeRate-API has an open endpoint with daily updates and attribution, plus a keyed free plan with monthly limits.
Finnhub and Twelve Data support forex alongside other assets, but exact real-time coverage and WebSocket access depend on plan.
Choose reference rates for reporting, indicative quotes for monitoring, and broker or venue streams for trading decisions.
Frankfurter 开源且无需 Key，提供多家央行每日汇率并可按数据提供方筛选。
ExchangeRate-API 有每日更新、需署名的开放端点，也有带 Key 和月度限制的免费套餐。
Finnhub 和 Twelve Data 同时覆盖外汇与其他资产，但实时范围和 WebSocket 权限取决于套餐。
报表使用参考汇率，监控使用指示性报价，交易决策应使用经纪商或交易场所流。
What “free” and “real-time” mean for this API这个 API 中“免费”与“实时”分别意味着什么
The phrase free forex API covers three different datasets. Central-bank reference rates are published once per business day and suit accounting, invoicing, and reporting. Aggregated indicative rates update more often and suit dashboards. Broker or venue bid/ask streams are needed when spread, executable price, and event latency matter.
Calling a daily rate real-time because the API responds instantly is a category error. The relevant timestamp is when the underlying rate was observed or fixed. A conversion service also needs to define base and quote direction, weekends, holidays, triangulation, and rounding.
A useful comparison therefore begins with the decision the rate will support. A travel calculator, month-end ledger, treasury monitor, and automated FX strategy have completely different freshness, provenance, and licensing requirements.
免费外汇 API 实际包含三类数据。央行参考汇率每个工作日发布一次，适合会计、开票和报表；聚合指示性汇率更新更频繁，适合看板；当点差、可执行价格和事件延迟重要时，需要经纪商或交易场所的买卖价流。
接口立即响应，并不意味着底层每日汇率是实时数据。关键时间戳是汇率被观察或定盘的时间。换算服务还要明确基准/报价方向、周末假日、交叉换算和舍入。
因此比较应从汇率支持的决策开始。旅行换算器、月末账本、资金监控和自动外汇策略，对新鲜度、来源和授权的要求完全不同。
Provider comparison: access, fields, and limits供应商对比：入口、字段与限制
| Provider供应商 | Free model免费模式 | Rate type汇率类型 | Best use适合场景 |
|---|---|---|---|
| FrankfurterFrankfurter | No key; open source; no daily/monthly quota stated无需 Key；开源；官方称无日/月配额 | Daily central-bank and provider-filtered reference rates每日央行与可筛选来源的参考汇率 | Accounting, reporting, historical reference会计、报表、历史参考 |
| ExchangeRate-APIExchangeRate-API | Open endpoint or keyed free plan开放端点或带 Key 免费套餐 | Daily conversion rates on free access免费入口为每日换算率 | Small apps and currency conversion小型应用与货币换算 |
| FinnhubFinnhub | Free personal-use plan个人用途免费套餐 | Forex data from multiple brokers; REST/WebSocket offerings多家经纪商外汇数据；REST/WebSocket | Multi-asset prototypes多资产原型 |
| Twelve DataTwelve Data | Basic free creditsBasic 免费积分 | Broad forex pairs; deeper streaming depends on plan广泛货币对；更完整流式取决于套餐 | Symbol coverage and unified API代码覆盖与统一 API |
Provider-by-provider notes: where the free tier stops逐供应商深挖：免费层在哪里结束
Frankfurter is unusually transparent for a free API: no key, open-source code, central-bank providers, historical series, provider filtering, CSV and NDJSON, and self-hosting. Its strength is reference data, not tick-level executable FX. Use the observation date and provider field so a daily fixing is never mistaken for a live broker quote.
ExchangeRate-API's open endpoint is easy to integrate and explicitly documents daily refresh, attribution, rate limiting, and caching. The keyed free plan removes attribution but keeps a monthly request allowance. It is a good fit for low-frequency conversion, not spread-sensitive treasury or trading decisions.
Finnhub is attractive when an application already consumes stocks, crypto, company data, or news from the same provider. Its forex offering can simplify a multi-asset prototype, but developers should identify the contributing brokers, quote type, session behavior, and personal-use boundary before treating the result as an executable market price.
Twelve Data provides a common schema for many forex pairs and other assets. The free plan is effective for testing symbols, intervals, and conversion logic; higher-frequency streaming depends on plan and credit economics. Estimate calls per pair and interval, then include reconnection and historical backfill in the production budget.
Frankfurter 对免费 API 来说非常透明：无需 Key、开源、多央行来源、历史序列、来源筛选、CSV/NDJSON 和自托管。它的强项是参考数据，不是逐笔可执行外汇；必须保留观察日期和来源，避免把每日定盘价误当实时经纪商报价。
ExchangeRate-API 开放端点易于接入，并明确说明每日更新、署名、限流和缓存；带 Key 免费层免署名，但有月度请求额度。它适合低频换算，不适合对点差敏感的资金或交易决策。
如果应用已经通过 Finnhub 使用股票、加密资产、公司数据或新闻，其外汇接口能简化多资产原型。但在把结果视为可执行市场价前，应确认上游经纪商、报价类型、交易时段行为和个人用途边界。
Twelve Data 用统一结构覆盖大量货币对和其他资产。免费层适合测试代码、周期和换算逻辑；更高频流式取决于套餐和积分。生产预算要按货币对与周期估算请求，并加入重连和历史回补成本。
The fields that decide whether the data is usable决定数据是否可用的关键字段
An official or institutional fixing for valuation and reporting, usually periodic rather than continuously tradable.
A provider-derived midpoint or aggregate useful for monitoring but not a promise that a trade can execute there.
A venue or broker bid/ask tied to size, account, market conditions, and a short validity window.
A rate plus direction, timestamp, rounding rule, spread or fee assumption, and sometimes a fallback provider.
用于估值和报表的官方或机构定盘价，通常按周期发布，不是持续可交易价格。
供应商计算的中间价或聚合价，适合监控，但不保证能按该价格成交。
交易场所或经纪商给出的买卖价，与数量、账户、市场条件和短有效期相关。
汇率还必须附带方向、时间戳、舍入、点差/费用假设，有时还需备用来源。
Which option fits your workload?哪一种选择适合你的工作负载？
Use a named central-bank or official reference provider, preserve the fixing date, and document the fallback policy for holidays.
A cached daily or hourly rate may be sufficient when the displayed amount is indicative and fees or checkout conversion are handled separately.
Use timely bid/ask or institutional indicative data, define stale thresholds, and keep source, observation time, spread, and notional context.
Use broker or venue quotes tied to account and size. Reference-rate APIs are unsuitable for execution, slippage measurement, or transaction-cost analysis.
使用明确的央行或官方参考来源，保留定盘日期，并记录假日时的备用策略。
如果展示金额只是参考，费用或结算换算另行处理，缓存的每日或每小时汇率通常足够。
使用及时买卖价或机构指示性数据，定义过期阈值，并保留来源、观察时间、点差和名义金额上下文。
使用与账户和数量绑定的经纪商或交易场所报价；参考汇率 API 不适合执行、滑点测量或交易成本分析。
A practical evaluation and implementation playbook可执行的评估与落地方法
Verify USD/EUR versus EUR/USD, cross rates through a pivot, precision, and rounding with known examples.
Define whether the API repeats the last business-day rate, returns no value, or labels the observation date separately.
Store provider, upstream source, observation time, retrieval time, bid/ask/mid, and whether the value is official or indicative.
Do not silently use a stale fallback for pricing or settlement. Surface freshness and require policy approval.
用已知样例验证 USD/EUR 与 EUR/USD、通过中间币种的交叉汇率、精度和舍入。
明确 API 是沿用上一工作日汇率、返回空值，还是单独标记观察日期。
保存供应商、上游来源、观察时间、获取时间、买卖/中间价，以及官方或指示性属性。
定价或结算不能静默使用过时备用值，应展示新鲜度并要求策略批准。
Common mistakes that make a free API expensive让免费 API 变昂贵的常见错误
Fast delivery of an old fixing is still daily reference data.
A midpoint is not an executable buy or sell price.
Inverting after rounding can create avoidable errors, especially in financial records.
A retrieval timestamp alone hides weekends, holidays, and stale reference rates.
快速返回旧定盘价，本质仍是每日参考数据。
中间价不是可执行的买入价或卖出价。
舍入后再取倒数会引入可避免误差，财务记录尤其敏感。
只有获取时间会掩盖周末、假日和过时参考汇率。
Where QVeris fits in the workflowQVeris 在工作流中的位置
QVeris is a capability discovery and routing layer for agents. It can help an agent find, inspect, and call financial capabilities, but it does not replace the underlying data provider's license, entitlement, or source-of-truth obligations.
QVeris 是面向 Agent 的能力发现与路由层，可帮助 Agent 找到、检查并调用金融能力，但不会替代底层数据供应商的许可、权限或真值来源责任。
- QVeris can help an agent discover currency, market-data, and conversion capabilities and inspect their schemas before use.
- Return base, quote, rate type, bid/ask or midpoint, observation time, retrieval time, provider, and upstream source with every value.
- Keep settlement, trading, and licensing policy outside the language model; capability discovery does not authorize money movement.
- QVeris 可帮助 Agent 发现货币、行情和换算能力，并在使用前检查数据结构。
- 每个值都应返回基准币、报价币、汇率类型、买卖价或中间价、观察时间、获取时间、供应商和上游来源。
- 结算、交易和授权策略应独立于语言模型；发现能力不等于授权资金动作。
FAQ
Frankfurter is strong for no-key central-bank reference data; other providers fit live indicative or multi-asset use. The best choice depends on rate type.
Some are; many free conversion APIs update daily. Read the observation timestamp and upstream source instead of relying on marketing labels.
It is better suited to reference, valuation, and reporting. Trading needs current bid/ask data tied to an executable venue or broker.
Terms differ. Frankfurter states commercial use is allowed subject to each underlying provider's terms; other APIs may require attribution or restrict redistribution.
Frankfurter 适合免 Key 央行参考数据；其他供应商更适合实时指示性或多资产场景，关键取决于汇率类型。
不是。有些是实时的，但许多免费换算 API 每日更新，应查看观察时间和上游来源。
央行汇率更适合参考、估值和报表；交易需要与可执行交易场所或经纪商相连的当前买卖价。
条款不同。Frankfurter 表示可商业使用，但仍受各上游数据方条款约束；其他 API 可能要求署名或限制再分发。
Sources, methodology, and update policy来源、方法与更新政策
This guide compares public documentation and evaluates providers by workload, data freshness, structure, delivery, legal use, and upgrade path. It does not treat a marketing label as proof of real-time coverage.
Provider features and commercial terms can change. Official documentation linked below is the source of truth; run a representative data test and obtain appropriate rights before production deployment.
本文依据公开文档，按工作负载、数据新鲜度、结构、交付、合法用途和升级路径比较供应商，不把营销标签当作实时覆盖的证明。
供应商功能和商业条款可能变化。以下官方文档是最终依据；生产部署前应运行代表性数据测试并取得适当权利。