I-Bond Rates API

GET

Know the exact rate and inflation components for US Series I savings bonds.

I-Bond Rates provides current and historical interest rates for US Series I Savings Bonds. I-Bonds are inflation-protected savings bonds with a composite rate made up of a fixed rate plus an inflation rate that adjusts every 6 months.

Try it — live request, no key required

Request

GETapi.apiverve.com/v1/savingsbonds

Verification

Format

No key required to try it. Get a key to use it in your app.

Example

{
  "status": "ok",
  "error": null,
  "data": {
    "period": "2026-10",
    "compositeRate": 4.26,
    "fixedRate": 0.9,
    "inflationRate": 1.67,
    "purchaseLimit": 10000,
    "minimumHoldingPeriod": "1 year",
    "earlyRedemptionPenalty": "Last 3 months interest if redeemed before 5 years",
    "taxAdvantages": "Federal tax deferred until redemption; exempt from state/local tax; may be tax-free for education",
    "nextRateChange": "2026-11-01",
    "lastUpdated": "2026-09-01T15:00:29.761Z"
  }
}

About the I-Bond Rates API

I-Bond Rates pulls data from the US Treasury Fiscal Data API. The composite rate consists of a fixed rate (set at purchase, never changes) plus an inflation rate (adjusts every May and November based on CPI). Historical rate data is available back to 1998.

What people use it for

Investment Research: Track I-Bond rates to optimize purchase timing around rate changes
Financial Planning: Factor I-Bond rates into inflation-protected savings strategies
Rate Tracking: Monitor I-Bond composite, fixed, and inflation rate components over time
Historical Analysis: Analyze historical I-Bond rates back to 1998 for trend research

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON: Default REST response
XML: Markup format
YAML: Human-readable
CSV: Tabular export
GraphQL: Query language
MCP: For AI agents

View all integrations →

Other ways to use I-Bond Rates

Same data, same APIVerve account, same credit balance — one key works on all of them.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.on VerveKit Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.on VerveSheets Ground an agent on itA cited, machine-checkable fact your model can't produce on its own.on VerveContext

Questions.

Common questions about the I-Bond Rates API.

Read the docs →

How far back does historical rate data go?

Historical data goes back to 1998, covering every six-month rate adjustment announced by the US Treasury. Every plan gets the latest active rate by leaving the parameter blank; paid plans can query any specific period using YYYY-MM format.

Where does this savings bond data come from?

All figures come directly from the US Treasury Fiscal Data API. The dataset updates monthly and tracks the composite rate alongside its fixed and inflation-adjusted components, matching official Treasury announcements.

Can I query historical periods on the Free plan?

No, filtering by a specific historical period requires a paid plan. Free plan requests return the current active rate details. Upgrading to Starter or higher unlocks the period parameter for historical queries.

How many rate lookups does the Free plan cover?

The Free plan covers 100 lookups per month at 2 credits per request. For larger projects, the Starter plan provides 100,000 lookups each month, which works out to about $0.30 per 1,000 calls or $0.0003 per call.

Can I use this bond data in a commercial financial tool?

Yes, commercial use is allowed on any paid plan. You can use the rates inside your financial calculators, planning platforms, or portfolio dashboards, provided you do not resell or redistribute the raw rate data directly.

Request parameters — GET /v1/savingsbonds

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Optional

Parameter	Type	Example	Description
`period`OptionalPremium	string	`2024-11`	Specific issue period to lookup (YYYY-MM format, e.g., 2024-11). Omit for current rates.

Example request

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curl "https://api.apiverve.com/v1/savingsbonds?period=2024-11" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Header	When	Value
`x-api-key`Required	Every request	Your API key. Header names are case-insensitive, so `X-API-Key` is the same header.
`Authorization`Alternate	Instead of the above	`Bearer <key>` — for clients that only expose bearer auth. Resolves to the same account and the same billing.

401 is the only auth verdict

A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.

Response — GET /v1/savingsbonds

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

Sample response

{
  "status": "ok",
  "error": null,
  "data": {
    "period": "2026-10",
    "compositeRate": 4.26,
    "fixedRate": 0.9,
    "inflationRate": 1.67,
    "purchaseLimit": 10000,
    "minimumHoldingPeriod": "1 year",
    "earlyRedemptionPenalty": "Last 3 months interest if redeemed before 5 years",
    "taxAdvantages": "Federal tax deferred until redemption; exempt from state/local tax; may be tax-free for education",
    "nextRateChange": "2026-11-01",
    "lastUpdated": "2026-09-01T15:00:29.761Z"
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`period`	string	`"2026-10"`	Issue period for the rate (YYYY-MM format)
`compositeRate`	number	`4.26`	Total annual interest rate combining fixed and inflation components
`fixedRate`	number	`0.9`	Fixed rate component (set at purchase, never changes)
`inflationRate`	number	`1.67`	Inflation rate component (adjusts every 6 months)
`purchaseLimit`	number	`10000`	Annual electronic purchase limit per person in dollars
`minimumHoldingPeriod`	string	`"1 year"`	Minimum time bond must be held before redemption
`earlyRedemptionPenalty`	string	`"Last 3 months interest if redeemed before 5 years"`	Penalty for redeeming before 5 years
`taxAdvantages`	string	`"Federal tax deferred until redemption; exempt from state/local tax; may be tax-free for education"`	Tax benefits of I-Bonds
`nextRateChange`	string	`"2026-11-01"`	Date of next scheduled I-Bond rate announcement
`lastUpdated`	string	`"2026-09-01T15:00:29.761Z"`	ISO 8601 timestamp of last data refresh

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Header	What it carries
`x-api-remaining-credits`	Credits left in the current cycle
`x-api-credits-used`	Credits spent in the current cycle
`x-api-max-credits`	The allowance for the cycle
`x-api-version`	Version of the endpoint that answered

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

Status	Meaning	What to do
`400`	Input was rejected	Read `error`; it names the parameter that has to change.
`401`	Key missing or invalid	Check the header name and the key value.
`403`	Key valid, but not permitted here	A key restriction or an IP allow-list — never a bad key.
`429`	Rate limited, or out of credits	Read `error` to tell them apart, then back off or top up.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Plan	Per month	Credits	I-Bond Rates calls	Per 1,000 calls
Free	Free	200	100	Free
Starter	$29.99	200,000	100,000	$0.30
Pro	$99.99	1,000,000	500,000	$0.20
Mega	$299.99	4,000,000	2,000,000	$0.15

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Compare all pricing tiers →

Call it from cURL — GET /v1/savingsbonds

No SDK to install — this is a plain HTTPS call to /v1/savingsbonds with your key in the x-api-key header. Swap in a real key and it runs as-is.

cURL

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2

curl "https://api.apiverve.com/v1/savingsbonds" \
  -H "x-api-key: YOUR_API_KEY"

Resources

GitHubapiverve/savingsbonds-apiSource, issues and the examples this page is built from.ReferenceI-Bond Rates API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/savingsbondsnpm apiverve-savingsbondsPyPI APIVerve.API.SavingsBondsNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Node.js — GET /v1/savingsbonds

Install the Node.js SDK, then call the I-Bond Rates API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — npm

npm install @apiverve/savingsbonds

Node.js

const res = await fetch("https://api.apiverve.com/v1/savingsbonds", {
  headers: { "x-api-key": "YOUR_API_KEY" },
});
const { data } = await res.json();
console.log(data);

Resources

npm@apiverve/savingsbondsThe published Node.js client, versioned and signed.GitHubapiverve/savingsbonds-apiSource, issues and the examples this page is built from.ReferenceI-Bond Rates API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

apiverve-savingsbondsPyPI APIVerve.API.SavingsBondsNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Python — GET /v1/savingsbonds

Install the Python SDK, then call the I-Bond Rates API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — PyPI

pip install apiverve-savingsbonds

Python

import requests

res = requests.get(
    "https://api.apiverve.com/v1/savingsbonds",
    headers={"x-api-key": "YOUR_API_KEY"},
)
print(res.json()["data"])

Resources

PyPIapiverve-savingsbondsThe published Python client, versioned and signed.GitHubapiverve/savingsbonds-apiSource, issues and the examples this page is built from.ReferenceI-Bond Rates API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/savingsbondsnpm APIVerve.API.SavingsBondsNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from C# / .NET — GET /v1/savingsbonds

Install the C# / .NET SDK, then call the I-Bond Rates API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — NuGet

dotnet add package APIVerve.API.SavingsBonds

C# / .NET

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");

var json = await client.GetStringAsync("https://api.apiverve.com/v1/savingsbonds");
Console.WriteLine(json);

Resources

NuGetAPIVerve.API.SavingsBondsThe published C# / .NET client, versioned and signed.GitHubapiverve/savingsbonds-apiSource, issues and the examples this page is built from.ReferenceI-Bond Rates API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/savingsbondsnpm apiverve-savingsbondsPyPI

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Go — GET /v1/savingsbonds

No SDK to install — this is a plain HTTPS call to /v1/savingsbonds with your key in the x-api-key header. Swap in a real key and it runs as-is.

req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/savingsbonds", nil)
req.Header.Set("x-api-key", "YOUR_API_KEY")

res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))

Resources

Also published for

@apiverve/savingsbondsnpm apiverve-savingsbondsPyPI APIVerve.API.SavingsBondsNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from PHP — GET /v1/savingsbonds

No SDK to install — this is a plain HTTPS call to /v1/savingsbonds with your key in the x-api-key header. Swap in a real key and it runs as-is.

PHP

$ch = curl_init("https://api.apiverve.com/v1/savingsbonds");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-api-key: YOUR_API_KEY"]);

$response = curl_exec($ch);
echo $response;

Resources

Also published for

@apiverve/savingsbondsnpm apiverve-savingsbondsPyPI APIVerve.API.SavingsBondsNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Ruby — GET /v1/savingsbonds

No SDK to install — this is a plain HTTPS call to /v1/savingsbonds with your key in the x-api-key header. Swap in a real key and it runs as-is.

Ruby

require "net/http"

uri = URI("https://api.apiverve.com/v1/savingsbonds")
req = Net::HTTP::Get.new(uri)
req["x-api-key"] = "YOUR_API_KEY"

res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
puts res.body

Resources

Also published for

@apiverve/savingsbondsnpm apiverve-savingsbondsPyPI APIVerve.API.SavingsBondsNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

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I-Bond Rates API

Try it — live request, no key required

About the I-Bond Rates API

What people use it for

Ways to call it

Other ways to use I-Bond Rates

Questions.

Request parameters — GET /v1/savingsbonds

Optional

Authentication

Response — GET /v1/savingsbonds

Response fields

Response headers

Errors

What a call costs — 2 credits per call

Call it from cURL — GET /v1/savingsbonds

Resources

Also published for

Call it from Node.js — GET /v1/savingsbonds

Resources

Also published for

Call it from Python — GET /v1/savingsbonds

Resources

Also published for

Call it from C# / .NET — GET /v1/savingsbonds

Resources

Also published for

Call it from Go — GET /v1/savingsbonds

Resources

Also published for

Call it from PHP — GET /v1/savingsbonds

Resources

Also published for

Call it from Ruby — GET /v1/savingsbonds

Resources

Also published for

Zero-code embed — one snippet, no backend

Changelog — I-Bond Rates API

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