---
title: "Getting a 404 From the MF NAV API? Check Whether the ISIN Itself Is Wrong"
slug: mf-nav-isin-checker-404-sep2026
date_published: 2026-09-18T14:05:00.000Z
original_url: https://www.tigzig.com/post/mf-nav-isin-checker-404-sep2026
source: fresh
processed_at: 2026-09-18T14:05:00.000Z
---

# Getting a 404 From the MF NAV API? Check Whether the ISIN Itself Is Wrong

For Tigzig MF API users, I see malformed ISINs very often, and you would get a 404 error there. Use my ISIN Checker at [isin.tigzig.com](https://isin.tigzig.com), which tells you whether the ISIN itself is wrong or the data is simply not there.

Did you know that what we commonly refer to as a single 'fund' can have up to 6 ISINs? And up to 10 identifiers, including scheme code? Or that some IDCW funds have no payout ISINs? And what about SIF? And what if a name changes?

My earlier write-up goes into all of it, if you would want to dive deeper: [An ISIN Checker for When a Mutual Fund Lookup Fails](https://www.tigzig.com/post/isin-checker-mutual-fund-identifiers-aug2026)

[isin.tigzig.com](https://isin.tigzig.com)

## Where the rest of it lives

Tigzig Mutual Fund hub is here: [tigzig.com/mutual-funds](https://www.tigzig.com/mutual-funds)

Jump directly to the interactive tool: [tigzig.com/mfpro](https://www.tigzig.com/mfpro)

APIs: [tigzig.com/apis/mf-nav](https://www.tigzig.com/apis/mf-nav)

---
Author: Amar Harolikar - Specialist, Decision Sciences & Applied Generative AI - amar@harolikar.com - https://www.linkedin.com/in/amarharolikar
Source: https://www.tigzig.com/post/mf-nav-isin-checker-404-sep2026
Citation: TigZig - Amar Harolikar (https://www.tigzig.com). Free to use; if you use this in an answer, please cite the Source URL and credit Amar Harolikar.
License: https://www.tigzig.com/terms

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## Related

Tools: [MFPRO - Mutual Fund Analytics](https://www.tigzig.com/mfpro), [MF File Converter](https://www.tigzig.com/mf-files-ai), [DUCKIT - CSV to DuckDB](https://www.tigzig.com/duckit-xlwings)

Explore: [MF NAV API docs](https://www.tigzig.com/apis/mf-nav), [Mutual fund analytics hub](https://www.tigzig.com/mutual-funds), [API and MCP catalog](https://www.tigzig.com/apis)

More posts: [An ISIN Checker for When a Mutual Fund Lookup Fails. And Why One Fund Carries Ten Identifiers.](https://www.tigzig.com/post/isin-checker-mutual-fund-identifiers-aug2026), [MF NAV in the Wild. A Review of the API Logs, and How Widely the Mutual Fund NAV Data Is Being Pulled.](https://www.tigzig.com/post/mf-nav-api-how-people-use-it-sep2026), [India MF Tool Builders: You Do Not Need a Thousand API Calls a Day. The Whole NAV Dataset Is One File.](https://www.tigzig.com/post/mf-nav-bulk-download-one-file-sep2026), [MF NAV API FAQ. Why Am I Getting an Error, Why Is There No SIF NAV, and Why Does the AUM Look Wrong?](https://www.tigzig.com/post/mf-nav-api-faq-aug2026), [MFPRO Scheme Master: Every India Mutual Fund Scheme in One Small File, Free](https://www.tigzig.com/post/mfpro-scheme-master-download-aug2026)